My understanding is that, regardless of level, 100 in both spellbook and realm skill is not enough to cast a level 7 spell at PL7 without a chance of failure.

Also, the loss of 4 levels will make your spells less able to penetrate magic resistance.

Not currently considering any class changes (though I am planning on doing one character replacement, though it occurred to me that a good time to do that would be after killing hte savant troopers by Vi Domina, but before talking to her (which I believe triggers an XP reward). On the other hand, I might opt to do something like the Priest->Lord change I mention in the other topic, but changing to Valkyrie instead, in order to get Power Strike faster than a pure Valkyrie, but that only works if the character is a Dwarf, not a Dracon. (Reaching level 5 for Armorplate/Magic Screen for the trek to Arnika is one option, for example. With that said, one does need to compare it to character replacement, which is worse in the short term but better in the long term.)

From a gameplay standpoint, replacing a character after rescuing Vi Domina is cheesy. Though I can't throw stones, as I killed the Savant Troopers holding Vi hostage, then recruited Myles after they were dead, so that he wasn't mad, and he and my party got the XP reward. I also dragged him along for the "Bank Liberation" quest, and dismissed him before fighting the slime, so that my party could kill it quickly, only to re-recruit Myles later, and grab the bank goodies, so he wouldn't be mad.
I thought about it, and the fact that I built my MDP for, well, magic damage, makes it impossible to switch classes to a more tough class. I will take my 25% to spellbook skill, and that will be my consolation prize, that I can cast level 7 spells at PL 7(125 skill).

is getting Power Strike 2 levels before really worth the effort?

are you going to have them both in the same party i.e, 1 priest dualed and 1 pure Lord \ Valkyrie

That first question's answer may depend on the player, and on the party they're using. Keep in mind that the hardest part of the game is Arnika Road (1st time), so favoring the early game in builds isn't an entirely unreasonable choice. (Then again, you're not going to have Power Strike/Cast at that point; even an optimal choice won't get either skill before level 9 (unless you count the Trynton fountain that you can't access before Trynton for obvious reasons).

If there's no other character capable of casting Heal Wounds, then starting as a Priest likely makes sense, so that you have access to Heal Wounds in the Monastery.

On my very first party (IIRC), I actually used a battle priest who, after learning both Power Strike and Power Cast, changed into Lord later in the game; this did end up working, though not as optimally as a pure Lord in the long run.

The plan for my party involves a Valkyrie (could start as Priest, but might choose not to), and for a temporary character for which Priest is one of the candidate classes (to be replaced with Gadgeteer in Arnika or Trynton).

Are you sure about that? So, you're telling me that, in theory, if I reach level 24 with all 4 pure casters, and get their spellbook skills to 125(100 natural with 25% class bonus), and all their realm skills to 100, and can cast their level 7 spells at PL7 because of the bonuses, if I class change, for example, Priest to Lord(No Valkyrie, as he's male), that he will take a 4 level spellcasting penalty? He should already have credit for 24 levels as a Priest. I understand that he won't be able to grow his magic abilities until 5 levels as a Lord(which doesn't matter, as he should have all Priest spells and every magic skill maxed by then), but I didn't think the game would retroactively punish me like that. I think the problem is that he would only have 100 to Divinity skill, not enough for Falling Stars/Death Wish/Restoration to be cast at PL7.
I seem to recall in one of my old parties, in which I would always have a Bishop, that she does get all-powerful at some point, casting her level 7 spells at max power, with a ton of SPs due to having 101 spells learned. Maybe I'm imagining things though, it takes a really long time to get a Bishop "maxed" with all spells, and Intelligence/Piety/Speed/Senses at 100 natural.
Character replacement seems kind of extreme. That character will perpetually be 5 levels or more behind the rest of the party. Then again, those first levels don't represent much experience loss, and they can catch up quickly. At level 5, you can only cast Armorplate/Magic Screen at PL1 safely. I waited for the Arnika Road dangerous part until level 14(very extreme) because I wasn't confident in my MDP's low-level magic. Not to mention those level 10 Higardi Brigand can do a number on a weak party.
We see eye to eye on the Bard and Gadgeteer's presence in the party. You want a Gadgeteer to replace whatever temporary character you created to get you to Vi Domina. I'm a big fan of the Gadgeteer, as her ability to create the Tripleshot Crossbow rocks, she does Locks and Traps(starts with 9 skill), and Engineering can be trained with the Lightning Rod in preparation for better gadgets later on(I sold the Jack in the Box, I don't want to scare away enemies, and Terror doesn't work on Savant machines).

With these particular spells, it's not that important to cast them at an unsave power level.
* First of all, these spells can't backfire; they can only fizzle, in which case the only things you lose are the turn and the SP spent (and you gain some skill experience).
* These spells are most commonly used outside of battle. Hence, you don't actually lose a turn, and you only lose SP.
* If the spell fails and you lose the SP, it's not a big deal, just rest up until you get the SP back, then recast the spell. (Note that you won't get more skill xp unless you save and reload, or (according to someone on another forum) wait 3 minutes since your last cast of that spell.)

This applies to other long duration spells as well.
(Note that, in the case of X-Ray, you don't even need to use that spell at a power level higher than 1; the only advantage of the higher power there is to increase the duration. It is, however, annoying when the spell wears off during battle and the game won't let you recast it.)

I don't like selling unique items like that. If I get such an item and I don't like it, I just leave it behind somewhere, as items left on the ground or in containers will not go anywhere (as long as you don't leave them in the Wilderness Clearing or the Rapax Away Camp, or in a certain area on Ascension Peak).

Note that you can even leave quest items behind in containers if you don't want to take them with you. Just be aware that placing 2 of the artifacts in a container in the Rapax Away Camp will softlock the game (you can continue playing, but the Camp will be replaced with the Wilderness Clearing, and you won't be able to retrieve the artifacts which are required to beat the game).

Also, in theory you can upgrade the Jack in the Box into the Demon in the Box, which casts Psionic Blast; it is the only gadget to be upgradeable in this fashion. Unfortunately, it's not possible (in the unmodded game) to do this in practice, as the Demon Doll is nowhere to be found.

At PL1, most of the buff spells don't last that long, and you're likely to be caught "with your pants down" in a battle where it expired right before battle, or it expires during battle, forcing you to waste turns re-casting them. I'm not a fan of "training" buff spells, rather, I use them when they are needed, such as after a rest to replenish mana after a battle or two.
I'm not too crazy about saving every unique item, as they take up space if left on the ground, causing me distraction, and may slow/crash the game if too many items are lying about. If I was to go down that path, I would put them in a treasure chest(the upper room in He'Li's bar is my favorite, as she said that I can have the room if I clear out the bandits, which I did). I do that with the Damaged Black Box, Marten's ID Badge, etc. Items that are useless to me, but can't be sold.
I take back my thoughts on class changing. For example, take my Priest. He is built for magic, as a glass cannon. He has devoted all of his attribute points into Intelligence, Piety, Speed, and Senses(something that any dedicated caster should have). He has totally ignored Strength, Dexterity, and Vitality(though it starts at 55, a profession prerequisite). Class changing would be impossible at this point, and even if I could, somehow, by allocating the attribute points, he has low skill points, or none, once new ones open, in decent fighting skills. Not to mention, I think that his(comparably) low HP in comparison to a fighting class(Fighter, Lord, Valkyrie) would not be made up for by class changing. I believe that the game would only award the extra HP for that one level that I switched, using the Priest's lower HP for most of the HP total(if you know what I mean).
I have noticed a significant day/night cycle in this game. I try to not be biased in what time it is, when grinding. However, I have noticed, on this last night cycle, that at night, only various Higardi thieves spawn, which is near the crashed spaceship where you save Vi Domina. The max level of these are level 10 Higardi Brigand, which for my level 19/18 party, aren't really worth the time to kill experience-wise(though skill-increase wise, they aren't bad). If I did my grinding during the day, I would get Savant machines from both spawn points(the Savant Tower in the West, and the Spaceport to the South).
I always cast spells at PL7 if possible, probably for the (possibly mistaken) belief that a higher power level will have a better chance at a skill increase. In particular with buff spells(Light, Armorplate, Magic Screen, Detect Secrets, Missile Shield, X-Ray, Enchanted Blade). Those are my big 7 for this party. I'm not too crazy about Shadow Hound(I don't rest in the open) or Chameleon(I heard that it doesn't work well with Light, and I'm trying to gain experience, not avoid it).

My point is that, even if you're only safely able to cast the spell at PL1, if the spell is a non-combat spell it's perfectly reasonable, even on Iron Man, to try and cast the spell at a higher power level. If the spell fails, just rest or drink some Magic Nectar; if it succeeds, you now have the spell in effect at a higher power level.

Sometimes, sticking to safe spell levels is not always the best option.

Another example, of course, is Identify Item and Remove Curse. If you try to cast the spell on an item that you can't identify/uncurse at the current power level, the spell will be cast at a higher power level, which gives you a chance of identifying or uncursing the item. Identify Item can't backfire, and while Remove Curse can (and may Hex the caster if that happens), there's only two situations where the backfire could cause a major issue:
* If the caster's HP is low, the loss of Vitality from the hex could lower HP to 0 or below, killing the character. You can prevent this by healing the character first.
* If you cast Remove Curse from the inventory, the spell backfires, and the hex from the backfire reduces SP below 0, the game will crash. You can prevent this by casting the spell from the main screen, though I've heard this crash might not delete your save even on Iron Man mode (because you didn't actually get a party wipe; this would be like force terminating the process to do what roguelike players sometimes call "save scumming" (I don't like that term)).

I'm pretty sure that casting the spells at PL7 does, indeed, give more chances for skill increases. Also, so does casting higher level spells.

This is why, if you're looking for spells to practice, spells that are not capable of backfiring, or that have harmless backfires (Remove Curse out of combat, Holy Water/Banish if the game allows you to cast either), are particularly good. For example, the Alchemist spellbook has a bunch of exclusive spells that are useful for that purpose, like Dracon Breath, Razor Cloak, and Ring of Fire; spells like these are especially useful if Alchemist is the Bishop's lowest skill. (Note that Alchemy is lacking exclusive non-combat spells, whereas the other spellbooks have at least one example at level 3 or lower (don't forget Hypnotic lure!).)

By the way, have you been able to get any good use out of either Sonic Boom or Hypnotic Lure?

They're also good for drops, particularly if you have a Bard in the party, not to mention that extra drops can be sold for money.

Incidentally, if you go to the Rapax Castle Main Level, and are able to kill the enemies that spawn there (assuming they're still hostile), preferably *without* having Ferro die, you can get lots of treasure, which you can then sell for money, providing a nice non-Alchemy way to get money to buy expensive items.

By the way, another money making trick is to get a character with a high Communication skill, buy items from Sadok T'Rang (at 90% price), and then sell them at 100% price elsewhere.

I agree with you on your first point. I just dislike wasting mana if the spell fails, particularly in those early levels in the Monastery, where you are not in a safe resting place(such as where the Light spellbook is found, or those two cells, one with the dead Rapax, the other with the set encounter roaches.) At level 1, if you didn't properly allocate skill points, sometimes you can't even cast a combat spell at PL1, forcing you to take the risk. I find the backfires on the Bard's instruments to be particularly annoying, as there is no way to control the PL at which is is cast(sometimes, I reload if she puts my party to sleep). By the time the Gadgeteer gets the Lightning Rod, you are usually at level 6 or higher, and have had more time to put points into Engineering(but it can still backfire, though I don't think it does anything if that happens). This is a non-issue now, of course, with Music and Engineering in the 90s. BTW, I managed to get my Mage's Wizardry skill up to 125(100 natural with 25% bonus). The 95 to Intelligence is probably the reason for that. The others are still lagging, with their spellbook skills in the high 90s.
I have wondered that myself. For example, is it better for my Mage to cast Nuclear Blast PL1, or Fireball PL7? I would assume that whichever costs more SPs would be the one with the better chance to increase the Fire realm skill. Usually, a lower level PL7 spell does more damage, but an exception would be the Higardi Brigand. They move so quickly, even with my casters at 100 Speed and Snakespeed unlocked, and Senses in the 60s/70s, that it's a toss-up who goes first. They may move first on Round 1 and get out of the way of my Fireball, or if I aim at my party, if I go first, I will miss them. In that case, Nuclear Blast is better, as it does guaranteed damage to everyone on screen(unless resisted, which they won't at level 10). By the way, Brigands have a 100% drop chance, excellent to farm those Bard items(I already have all 3). It's a good money maker to sell those items, but at this point in the game, I already have around 600K gold.
Sonic Boom is not a good idea for my MDP, as you don't want to scare enemies away. Hypnotic Lure is good for crowd control, and it can be used outside of combat, but if it grants skill increases, I consider that cheating. I find the sound to be very annoying, however, and it sometimes can produce weird side effects. I can recall on 2 occasions that it made enemies go to inaccessible locations. Once, in the Rattkin Tree, it made a Swarming Wasp fly off of the rope bridge into the abyss. Another time, in the Swamp, it made a creature(I forget which) enter inside a big rock. Needless to say, I reloaded both times. I wasn't going to have a glitch rob me of kills. Neither will I let blinding or fear rob me of kills.
Speaking of cheats, I don't know if casting Summon Elemental outside of battle counts towards skill increases. I won't cast it unless enemies are around, however. I think someone mentioned that you can attack your own elemental, turning it hostile, and you can get an easy kill and skill increases. Being low-level, I imagine it would be easy, but they do have a lot of HPs, I think(good for training in that case.)
I have enough money that I don't need to do the Sadok trick. I have noticed something weird about Sadok though. He is yellow(neutral) at first, maybe because he doesn't fully trust you yet, but he will still trade with you. It takes a certain about of time before he will go green(friendly), but that doesn't seem to make any difference except for pixels(the same with T'Rang Youngers spawning from the spaceship). Also, Sadok sometimes will glitch out, if he gets himself stuck in the door(him moving around randomly and opening the door randomly is pretty annoying, as you can't safely sleep there).

That's never the case for me the way I tend to play the game.
* I always leave the Monastery at level 5, and the Lightning Rod is in the Monastery, hence I find it with a Gadgeteer at level 5 if I'm using one at the start. (At level 6, Pestilent Rats appear in the Monastery, and they can cause disease, which can lead to permanent stat loss if not cured, and there are no Cure Disease or Restoration potions in the Monastery.)
* If I do a character replace to get a Gadgeteer later, she will only be level 1 at first, yet I'd give her the Lightning Rod right away (since I have it at that point in the game). With that said, note that the plan is to do this right before getting quest XP, so she will be higher than level 2, but still won't be level 6 before I win a battle with her (unless I do something strange, like turning in the Umpani Traitor for an XP reward; you can get tons of XP quickly, but it comes at the cost of an important shop, and will likely take other party members up to a higher level without them developing skills to a suitable level).

(I'm most likely to get enough XP to reach level 6 if I put a priest in my party and have her pray for a miracle religiously.)

It can grant a skill increase, but it has a practice timer; unless you save and reload, re-casting the spell within 3 minutes of a previous cast will not grant a skill increase. (This is the same way spells like Armorplate usually behave.)

The main reason I ask about this spell is that I tend to get the Lava Lamp before any gadgets I consider generally useful.
If these enemies like to go into melee range, this would be an ideal situation to use the Alchemist spell Ring of Fire, as it does its damage at the end of the round, instead of immediately.

(Incidentally, this is the sort of reason that one might justify having an intentionally slow spellcaster in the party; just cast a radius attack spell or Heal All, and it should go after the enemies have charged into melee range or done damage to the party, allowing the spell to function. Might be interesting to try a 2 Bishop party, one who focuses on Speed (too bad Fairies have crippling equipment restrictions), and one who intentionally has poor Speed/Senses.

Sadok T'Rang doesn't help you out in combat, which makes sense because, if he did, he would risk dying and you would be out a merchant.

Ferro Rapax, on the other hand, *does* help you out in combat, and this can lead to a situation where he dies helping you, through no fault of your own, and you lose access to the best merchant in the game. They really should have made Ferro more like Sadok in this regard. In some cases, it may be necessary to use spells like Freeze Flesh (not Freeze All!) and Psionic Blast to keep him alive, as those spells can hit through walls, just as long as the enemy group name appears on top of the screen.

There is a situation where Fireball can hit enemies that Nuclear Blast can not.
* Nuclear Blast hits all visible enemies in range. Note that this does not include enemies that are just around the corner, out of sight.
* Fireball must be centered on a visible spot. However, the blast hits everything within the radius and line of sight from where the center is placed; this *can* hit an enemy that's just around the corner, and I believe it may be possible to hit an enemy that's out of range. Not as good as Psionic Blast at this sort of thing, but it is still an option.

You don't need to worry about the Umpani Flag, as the game would not (intentionally) deprive you of the ability to complete the Main Quest.
* To turn him in, I believe you need to ally with the Umpani, and I have a feeling that the T'Rang may not like it once you turn in their spy, so you likely don't have a use for the flag at that point.
* If you kill Kunar, he always drops the Umpani Flag, so you should be able to do the T'Rang quests. (He also drops the fake key card that you need to do the final T'Rang quest, if you feel like it.)
* In case the T'Rang are hostile, Z'Ant will always drop the T'Rang-Mook Letter.

This does beg the question: How can Kunar spy for the T'Rang before the T;'Rang know the Umpani are around (that is, before you do the quest to retrieve the flag, or the Umpani quest to bring back part of a T'Rang)?

I was looking at the armor situation for the Faerie race, with the idea of perhaps adding SP regen to some piece of equipment (if I mod the game), and the situation is rather appallling:
* Zynaryx Plate is the strongers, but it's a custom item that require 3 items, 2 of which are random drops.
* Canezou Robe, but it's a quest item that you're not likely to get before the Robe of Rejuvenation, and it's usable by all characters anyway
* Ninja Garb, but that's Ninja only (and is usable regardless of race)

Which leaves the Gossamer Gown, which is a really early game item.

Incidentally, what if Bela sold the Ring of Power? It would help with the SP regen situation pre-Ferro, and would not discriminate based off race, not to mention all the pure casters can use it. (Actually, the only classes that can't equip it are Fighters and Rogues, who don't need SP regen unless they're the prior result of a class change.)

Perhaps an easy mod to increase availability of some items without unbalancing things too much would be something like this:
* Lord Braffit now sells Holy Water spellbooks. (Maybe Sadok; one could even justify Fuzzfas, since he sells the item, even though the spell would be of no use there.)
* Anna now sells Mind Stab spellbooks. (This item is dummied out, but it feels like it ought to have a location.)
* Bela now sells Rings of Power. (The only way to get the item in vanilla is for Bela to die, which is a problem because he can't be targeted, so you can't fight him the conventional way; he can only be damaged by missile attacks that hit him instead of the intended target and by spells that backfire.)

Ther3e are some other ineteresting items that are sadly rarer than they should be that would be nice to be able to purchase, but there isn't an obvious place to do so:
* Frontier Phaser (at least Jan-Ette can drop this, so reloading to try and get this isn't a problem, but you may have to choose between that and the *Light* *Shield*)
* Cobaltine Powerglove (the one fightable enemy that drops this is special in that his death triggers the ending sequence, so you don't actually get to use it)
* Solar Powerpacks to charge them up
* Mystery Ray for an early game energy weapon (it apparently imports)
* Faerie gear, including things like the Rod of Sprites and the Fey Ring (though the latter might be underpriced)
* The *-mancer rings that boost magic skills
* Ring of Beasts (though that's not too hard to get if you turn the Rattkin hostile)

And many others.

Edit: One other change:
* Infinity Helm no longer regenerates SP. (It feels rather absurd that the best SP regen item, by far, is not equippable by pure casters.)

The Rapax are good sources of treasure, though, especially if you want a chance of affording expensive equimpent without using Alchemy. (Infinity helms are 150k, and robes of rejuvenation 100k.)

Maybe Kunar being a spy before the T'Rang "know" of the Umpani base is one of those things that wasn't fully thought out(kind of like that brazier in Trynton that does nothing). I guess sometimes you have to suspend disbelief, and enjoy the game. I just assume that Kunar is a regular, disgruntled Umpani, fed up with the bureaucracy(there are plenty of those working for any given company), until I know better.
The only custom item ingredient that is hard to get IMO is the Vampire Bat Wing. They only spawn from Vampire Bats, not Bat Vampires, and even then, there is only a 5% chance to drop. I think that the odds of an encounter can be increased if you are outside at night(similar to how in Arnika, you fight Higardi thieves at night and Savant machines by day). You could always kill all but one bat, and farm the last one for the wing. That's what I did in the Monastery.
I think that the Canezou Helm is great for everyone(at least most) because it has good AC and gives + to Vitality, which is rare to find.
Both Holy Water and Banish are rarely used by me, because they're situational spells. They only affect a rare enemy type, undead(and demons for the latter). The only reason my Priest has Holy Water is because the spellbook is free if you can farm it from the Savant Orb, which wasn't too hard to do. I wouldn't have picked it at level up unless it was one of the last choices. Same with Banish, pretty soon I can outright buy it from Braffit, no need to waste a spell pick.
I never understood why Mind Stab doesn't have a spellbook like every other level 1-5 spell. W8 was released under hard circumstances, so it is what it is. I guess it's only a small issue for a Bishop, the Psionic doesn't have to worry too much about saving spell picks.
I always turn the Rattkin hostile, the best faction rating you can have with them is neutral(they start out like that). They have great item drops(I once farmed the Ring of the Road for the Bard, and the Tinker's Carryall Bracers for the Gadgeteer...+20 to Strength for both items). From a role-playing perspective, the Rattkin, like the Rapax, are not very pleasant characters, and they invaded the 6th Bough, so they are the aggressors(including Don Barlone and Milano Calzone). I usually do a full wipe of the 6th Bough, so the Trynnie can have it back.
I find that the Rapax drops help the most at the beginning of the game, if you can manage to find a wandering pack of Rapax Scouts in Trynton. They can be tough at this point in the game, though, which is one of many reasons that I'm training up my magic skills almost to 100 before that point. Even if I can kill Al-Sedexus without triggering the Rapax, rescuing Drazic and Rodan will end my good standing with them, so it's pointless.