Even more epic party:

Valkyrie, Samurai, Monk, Ranger, 2 Bishops

All go for INT, then DEX and VIT, powertrain Reflections, Iron Skin and Shield to 100, after that dualclass everyone to Monk for one level to powertrain Stealth and Critical Strike (optionally Ranged Combat + Throws with infinite Shuriken)

Pros: 6 portals
Cons: only 20 pick locks from 2 items (can use divine trap and knock to partially negate)

Even more balanced party (though one that, unfortunately, Wizardry 8 won't allow you to start the game with):

0 characters. (That is, an empty party.) Here are the perks of this party:
* Everyone is exceptional at melee combat.
* Everyone is exceptional at ranged combat.
* Everyone is exceptional at spellcasting.
* You don't need to worry about characters dying, because there are no vulnerable characters in the party.
* Encumbrance could be a problem, except that there's nobody in the party who would actually get encumbered, and everyone has 100+ strength, anyway.

(Although, to be honest, if you were somehow able to get in-game with such a party, the game would probably crash wish an assertion at some point. Even if it didn't, it would likely do something like trying to divide by 0, which could also crash the game.)

I don't like to give hybrids Powercast, leaving Intelligence at base (the whole party benefits from +5 Intelligence from the Trynton Well). The thing is, especially with Divinity and Alchemy users, there are plenty of defensive healing, curing, buffs, and utility spells that don't need Powercast to be effective (I know PC increases the duration of buffs, and I think heals more, but it doesn't seem necessary). The opportunity cost for maxing the Valkyrie and Ranger's Intelligence would make them less effective at what they do best, physical combat.
I prefer to go Strength and Dexterity first (Powerstrike and Reflextion), and then Speed and Senses (Snakespeed and Eagle Eye). This will make the Fighter, Rogue, Valkyrie, and Ranger hit hard, fast, and often. This combination of 4 attributes gives the best possible chance to hit, highest number of swings and attacks, ensures they always go first, and makes them hit the hardest (Intelligence/Piety/Vitality don't factor into any of that).
The party you described is a hybrid heavy party, with two good magic users, and four decent magic users, who can all do melee/ranged/magic. It's a little lacking in the melee part, which is why I brought along a Fighter and Rogue (they're a lot of fun working together, and although they have no magic, at least the Rogue can do Locks and Traps, and both the Fighter and Rogue hit very hard in melee).
The Bishops are more debatable. They are doing two spellbooks at a time, and will do the other two ignored ones later, once good level 6 and 7 spells are learned. They are starting to pick the good level 5, 6, and later level 7 spells in their first two strongest spellbooks (note that Ferro is a pain to get to, while the other vendors can be reached with relative ease).
Pretty much everyone agrees with Intelligence and Speed (Powercast and Snakespeed). You want your primary casters able to pierce resistances, and to go first with the protection spells. To that end, my Bishops have 95 Intelligence before the Trynton Well, and 100 Speed. They will now be working on Strength and Senses (Powerstrike and Eagle Eye), making them very versatile. Note that the casters can't entirely rely on magic (against bosses and higher level enemies, some physical damage is needed, whether from melee or range).

I train all 4 schools for Bishops, takes effort but worth it :)

Same, though I'm considering not doing it as much for battle bishops.

Some day, I may re-create that recent MDP I started, but make the battle bishop a dwarf. Power Cast comes much later (level 17 of so instead of 12 IIRC), but Power Strike might only be delayed 1 level, and the character will have better survivability (the human in that slot did die a few times IIRC).

Then again, I have other games to play, many of which are around 15 years older than Wizardry 8.

A Bishop with 4 spellbook skills (Wizardry, Divinity, Alchemy, Psionics), and 6 realm skills (Fire, Water, Air, Earth, Mental, Divine), plus Powercast, can take a long time to train. This is why I'm hanging out in the Monastery. Everybody knows how tough the first stretch to Arnika can be. I want to be around level 20, where I can dominate the map (note that at my level, when I get to Arnika, I will be facing off against level 17 Savant Berserkers, level 21 Savant Slashers, and level 22 Savant Minion). So I have to prepare.

Arnika Road isn't that hard, assuming you're not in a certain level range.

At level 3, it's quite easy, as enemies can only spawn up to level 4. The non-random encounters can be a bit more dangerous, but are still manageable; the random ones are not an issue at this level. (At level 3, Gregor is more dangerous than anything on Arnika Road.)

At a high enough level (where "high enough" is probably much lower than your current level), there are no stronger enemies that can spawn, and you will, in fact, outlevel anything you could encounter on the road. The level where this happens varies from area to area, and for Arnika Road in particular it's actually quite low.

I could call it "cheating", as you have level 3 characters on the Arnika Road, way earlier than the game developers intended you to play (you have to beat level 5 Gregor). You could say the same for me, playing on Novice difficulty, grinding way higher than was intended for the Arnika Road first time. But I digress, everybody plays the game differently.
What I am really trying to avoid is the level 10 Higardi Brigand. They move ridiculously fast for their level, and sometimes, will act before your characters with a superior level. Around level 20 or so, you should be able to crush them. However, once you get to Arnika, you will meet level 21 Savant Slashers and level 22 Savant Minion. So you cannot truly dominate.

Level 18:
Valkyrie: Lightning
Ranger: Draining Cloud
Divinity/Wizardry Bishop: Restoration
Alchemy/Psionics Bishop: Quicksand

The Valkyrie and Ranger have 70 skill in their first four realms (Water, Air, Earth, Divine, and Fire, Water, Air, Earth realms, respectively). The picks were so that they can branch out into their fifth realm training (Fire and Divine realms, respectively).

Restoration (dtgreene's favorite) is decent, even at power level 1, while Quicksand, a level 6 spell, can be cast safely at power level 5, to kill enemies around corners, or even to kill enemies out of range if you carefully place your cursor at max distance.

I actually just read elsewhere about another interesting use of multiclassing, which can be used to create a variation on the battle priest.

The build is as follows:
* Create a placeholder priest in that slot. Consider putting points into Mace & Flail to start with a mace. (This is done for the equipment.)
* Replace the character with a Dwarf Fighter. Max out Str and Dex, and make sure Pie is high enough to change to Priest at level 2. (IIRC the requirement is 60, but double check. The Vit requirement is a non-issue.) Put skills in the weapon type you intend to use (I'd recommend Mace & Flail, particularly if that's the previous choice you made.)
* At level 2, change to Priest. Continue raising Str and Dex.

Note that the race has to be Dwarf here; Dracon won't work because starting Pie will be too low, to the point where you might consider just making a Valkyrie or Lord instead.

So, what this gets you, in comparison to a single-class battle priest, is the following:
+: More Str and Dex at the start. This means you'll be more effective faster. (Reportedly, Power Strike comes at level 11 with this build.)
-: One level behind in Priest spells. This isn't *that* big a deal, as penetrating enemy resistance is not as important for a Priest as it is for others.
+: But that doesn't apply to SP.
+: You do get Fighter HP for the first level, and with the first level counting double for HP, this is particularly nice, especially early in the game.
+: You also get a level of Fighter attack bonus, meaning that, in terms of fighting ability, you're actually one level ahead of a single class priest.
-: As mentioned above, Dracon isn't an option for this build, so you can't get a breath attack.

If you're at the point of maxing out your magic skills, you really should be at Ascension Peak, not Arnika.

I have been thinking more about Priest builds, including:
* Dwarf Fighter 1 -> Priest, Str/Dex, as a powerful variation of the battle priest build. An interesting option is to change back to Fighter later, after learning important spells.
* Gnome Priest. Str/Int, maxing out Int at (it looks like) level 12. You get Power Cast early, but at the cost of not getting Power Strike until late. (I think Reflextion might be learned at level 25 or so, around the time when the game would end if you've been exploring and not avoiding battles.) (Note: This race isn't good for high speed set-ups; a Gnome Priest will be slow, and will therefore want to focus on spells like Heal All and Purify Air that work nicely at low initiative.)

Those are two different builds that will lead to two very different uses of that class, and are good in different parties.

I apologize, I kind of bypassed what you said earlier, it's just that I wanted to get my point across, and I don't particularly like multi-classing. To your point, however:

I ran a MDP last time, and found that the Priest had a limited amount of attack spells, compared to the Alchemist, Psionic, and Mage. To the Priest's credit, they do get Restoration, Resurrection, and Death Wish, while Falling Stars is inferior to Earthquake.

A Battle-Priest, just like a Battle-Bishop, will be inferior in skill and levels to even a Bard or Gadgeteer. Note that the former are tier-3 characters, while the latter are tier-2 characters, in terms of chance to hit, and number of swings and attacks, I believe.

I'm doing a grinding run with Bishops, meaning that maxing all important skills will be extremely slow (as well as levelling up), but I will wind up with an epic party in the long run.

Advocating for a slow Priest or Bishop assumes that you will have an enemy that will cast cloud spells at your party; Thankfully, these are few and far between. I believe that there is only one battle where that is guaranteed, at AP, with Djinni of the Clouds at the Chaos Temple. In that one battle, you could just do what I do, and wipe them out in round 1 with fast magic/ranged attacks.

I'm kind of with you, but not really. What I'm going for are versatile Bishops. They already maxed Speed (unlocking Snakespeed), and have Intelligence at 95, waiting to max Intelligence, and unlock PowerCast, at the Trynton Well. At this point, they are working on maxing Strength and Senses, and will unlock Powerstrike and Eagle Eye around level 30 or 31 (way too late for most players, but I like to dominate the game).

A Bishop with maxed Strength, Intelligence, Speed, and Senses seems to be the way to go, as that gives them Powerstrike, Powercast, Snakespeed, and Eagle Eye, making them extremely versatile, with the bonus that no other class gets, the ability to cast any spell in the game. That seems like something to shoot for.

Edit: Note that in my last MDP, the Bard and Gadgeteer had *Light Swords* and *Light Shields*, making them powerful, though not as powerful as a Fighter or Rogue (it's about as powerful as said classes can get in melee). The Battle-Priest or Battle-Bishop would probably be best wielding the Staff of Doom, as they can hit from extended range, and don't have to worry about being hit back most of the time.

But can you do that at the levels the game is expecting? (I'm thinking around level 24 for endgame, but many experienced players get there a few levels earlier simply because they know where everything is and end up not fighting as many battles as a result.) Your magic won't be as effective when you're not at the high levels you seem to like.

Also:
* Heal All allows you to heal characters who haven't taken damage as of the start of the round.
* If you cast Resurrect too early in the round, there's a higher chance that the revived character won't survive to the start of the next round.
* There's the opportunity cost of raising Speed/Senses, in that you can't raise other stats instead. If you ignore initiative, these stats are of limited use (though high Speed does help you get extra attacks/swings, at least, though that won't help spellcasting).
* Having average speed really isn't ideal for healers. You can't consistently act first, but you can't consistently act last, either. This means that you could end up eating two full rounds of attacks without having a chance to heal.
* If you kill the enemies too fast, other characters won't get a chance to act, and hence won't get skill experience this round.
* In Continuous mode, being fact isn't as much of an advantage when it comes to healing. In fact, you can have a character defend, and if someone needs a heal later in the round, you can switch the character's action mid-round. (You can't do this in Phased.)

Or you could go in the front row with the Diamond Eyes (only one guaranteed, but this means you don't need to give the character the only guaranteed Staff of Doom, and can give it to someone else) or The Mauler (can buy multiple from Ferro). (In my experience from last playthrough (abandoned early because I was getting bored), a human battle bishop is a bit frail in the front ranks; she had a few deaths. On the other hand, a dwarven battle bishop should be more durable, but the one I used was not a front liner, so I sort of want to try one in the front.)

There's also, of course, the strategy of not using close range weapons and only using extended range. This would put, in the front ranks, the following sorts of characters:
* Polearm users. Fighter and Valkyrie are particularly good choices here, with Fighters being more powerful due to the overpowered Berserk ability.
* Giant Sword users (must be Mooks). Fighter, Samurai, and Ranger are good choices here. Again, Fighter is the most powerful.
* One Staff of Doom user. Any class could work, though Bishop may want to choose a durable race such as Dwarf, and I wouldn't recommend Psionic or Mage for this. Again, Fighter works best (and you even get a KO, in addition to the other effects it has), but you can use other classes here. The one class I wouldn't recommend for this is Rogue, because I believe you can't backstab with it, and backstabbing is really the only reason to use a Rogue over another class.


Also, the Light Sword/Shield are rare, and the shield looks so powerful that I consider it to be overpowered and won't use it.

(Also, note that the MDP I'm thinking of, that only uses full casters and no stamina casters, has nobody to use that sword.)

You really should hurry to Trynton, so you can start gaining Power Cast points.

The problem with making the character too versatile is that you can end up with a lack of focus, and a character who really isn't good at anything. With that said, Wizardry 8's system where skills improve by use with diminishing returns mitigates this factor somewhat (compared to games with pure skill point systems), but you might still need to choose 2 or 3 things for a character to be good at.

I'm half-thinking of using Cosmic Forge's DLL injection option (I think that's what it is) to change hard-coded things and seeing if I can turn Priest (but not Bishop) into tier-2 in terms of combat ability. This would make battle Priests more useful and make there be more of a reason to take a Priest over a Bishop.

(Be interesting to see how a Gnome Str/Int Priest with increased attack rating growth feels. Having Power Cast on a character with expert attack growth (what I like to call this tier) is something that doesn't make sense in vanilla, but might make sense in this mod.)

(Of course, I should check to see if Cosmic Forge can change this value with DLL injection.)