I tested this with a bit of hacking. A level 4 half-giant psionicist heals 2 HP per use of the power. Note that this power is actually not self only, but can target allies as well. Unfortunately, you need to re-select the power every time you use it, which can be a pain.

So this is summons-only genocide? That's pretty wacky. I'm having trouble imagining how fun this would be since so much combat functionality isn't usable.

It's pretty tough to kill with just spells alone (the non-attack spells are often far more effective), so by going Disarmed Enchanted Rajaat's Champion you achieve most of this challenge's goals.

I suppose a full genocide option (like Rajaat's Simulacrum) makes sense.

Bumping because I'm putting my magic where my mouth is!

I took two runs at Abandoned Mortal Rajaat's Champion [Mul]. It seems impossible, and mainly I just haven't figured out a character that will work for Abandoned.

I made a halfling Druid/Psionicist with the plan of gaining a level and leveraging Mass Domination to stay alive in the arena. Problem is, I couldn't gain a level! After barely surviving the first battle with 3 sligs and 1 screamer beetle, I had used every last arrow, spell, and psp. I did all the quests I could but came just shy of 4000 XP. In fact saving Semyon should have gotten me within just a few XP, but the 750 XP reported as a reward was incorrect. I'll log that bug later.

The second run was with a thri-kreen Druid/Psionicist. I thought the improved AC, movement, and extra attacks would help. But I got creamed in the first battle. My morale was already down, so I just abandoned the Abandoned challenge for now.

Here's the challenge I'm running now:
Enslaved Mortal Rajaat's Champion [Mul]

My party looks like:
Halfling Druid/Psionicist
3x Half-giant Gladiator (AI-controlled)

The arena went much easier, obviously. I went for the quick and silent escape from the sewers, and my guys all leveled up with extra XP.

It's not over. Enslaved is a massively difficult challenge since the AI will be terrible in combat with any spellcasters. As each of my gladiators falls, that's it... I expect my party to consist of just the halfling by the time I hit the Final Battle.

More on this later!

EDIT: I updated the challenge conditions with the reminder that you can (and should) max out HP at character creation. This was an optional AD&D rule that became de facto standard in the groups I played with in P&P, and today it is part of the official D&D rules.

Here are a couple I thought of.

First, a minor challenge that might be reasonable to impose in an otherwise normal playthrough:

First Dominate: A character may not learn Mass Dominate without learning Dominate first. If that is not enough, you could add that the character must be at least level X to learn Mass Dominate, or add some restriction about upgrading Mass Dominate.

Second, one that might expose a quirk in the way the game handles HP gains:

Frail: At character creation, all characters must start with minimum HP. Further, you must reload if you get more than the minimum possible HP at level up. (I predict that you may have trouble doing this and might sometimes gain more than the normal maximum HP gain.)

I prefer just taking away Mass Domination altogether, it's frankly too busted unless you're playing under other handicaps.

That's the goal of the Templar challenge; all of those spells allow the player to completely invalidate or avoid threats. I chose only the low-level area traps like Entangle because they can be spammed and don't have much competition for slots from other spells of that level.

I'll add Frail, but let's allow the die roll to grace the player. The reload would be really annoying to do.

I happened to look at the Wake of the Ravager manual, and according to it, you have to master Dominate before learning Mass Dominate. (That line wasn't in the Shattered Lands manual.) Is that, in fact, the case?

I'm wondering if the Templar challenge should disallow Energy Containment; it makes you immune to spells and psionics and has no maintenance cost.

I tested WotR and Mass Dominate can be learned before Dominate. On the other hand, it seems that Detonate can't be learned or improved on level up.

No maintenance is a pretty big deal, so yeah I'll add that one.

Update on my game as Enslaved Mortal. I dropped the Rajaat's Champion challenge because there aren't many muls besides Chahl, and well... I forgot about it. >.>

Headsmasher died to a wyvern sting in Cedrilte. Part of me was surprised I had made it that far without any casualties. I had a few close calls in Dagolar's domain, but otherwise my half-giants couldn't really do wrong with their brute strength.

The real problem came from a bug similar to Laussa's. On finishing Gedron, my character swung too much at Wyrmias and hit the statue. Combat did not trigger though, and he left. I should have thought the better of it, but part of me was curious as to what would happen. Well, the Final Battle didn't trigger. No freeze like Laussa though, I just get teleported to the area where everything remains as it was before. If I go back to Teaquetzl and leave again, I get sent back to the ruins where leaving again produces the same result. At least I have this used up genie bottle as a souvenir!

I regret my curiosity since I really wanted to fight the Final Battle as Enslaved, but I'm confident I would have won. I'm also not 100% the bug is caused by damaging Wyrmias since I did a few other things differently... but I'm pretty sure.

The plan now is to move onto the second game with my party as-is (2 half-giants and 1 halfling), same challenge.
EDIT: Well, Ravager doesn't keep the AI on. I feel like I read that somewhere and just forgot. Since I can't do Enslaved, I'm left with Mortal. I'll probably try out a couple new challenges to make up for it.

Here's another idea: The 4 Elements:

Every character must be a Cleric, and no two can choose the same element.

If desired, one could add the following rules:
Multiclassing is allowed, but characters must still stick with their clerical weapon restrictions.
Preservers are not allowed to use elemental themed arcane spells unless the element matches the character's elemental sphere. (So no fireball if you aren't Fire, for example, or Lightning Bolt if you aren't Air.)
Optionally, Druid is allowed, but any druid is not allowed to wear any armor regardless of multi-classing.

I think I mentioned an Alternative Healing challenge before, but here it is again (though this might be slightly different):
Divine healing spells are forbidden.
Arcane and Psionic healing is explicitly permitted (so have fun using Vampiric Touch after Lending Health to allies).
In Ravager, purposefully killing and Reincarnating characters is explicitly allowed. (I believe that restores the character to full.)
As a special case in Ravager, it might be interesting to allow the Altruism and Soothe spells to be used.

Here are a couple I thought of:

Always Active:
You are not allowed to use the "Guard" or "End Turn" commands. If you are in a situation where you are unable to do anything else except Wait and you've already Waited this round (in other words, the game can't continue without choosing "Guard" or "End Turn"), that counts as a defeat and you need to load your last save.

Tool-Assisted Upset:
This one will need tool assistance. Start a new game of Shattered Lands with the default party. After the defiler defeats the ravager, set the party to AI control and then lose the first arena battle. Changing equipment before the fight is not allowed. (Note that, if the ravager defeats the defiler (which is usually the case), then the attempt failed and you need to try again.) I consider this to require tool assistance because of the luck manipulation needed here.

Of note, in my test runs, I actually did see the defiler get lucky and defeat the ravager once. (The ravager's attacks kept missing a lot.)

I like the Cleric (Priest) idea, let's open it up to multi-class since we already have the Troop challenge. It's essentially a mandatory character dilution, but there's plenty of flavor to it as well.

Alternative healing just doesn't read to me as challenging. There are so many conveniently placed rest locations, I rarely use healing myself and certainly don't require it. I could see no healing at all being a challenge.

Always active is clever -- but my first impression is that this just boils down to getting through the arena. After you collect 4 bows there are virtually infinite arrows in Shattered Lands. And Ravager wouldn't be a problem.

What luck manipulation are you referring to for the Upset? You can position the characters before the fight, but I don't see any other parameters to work with. Also, I think this falls into the same bucket as a stalemate. It's stimulating to think of other 'modes' for the games, but non-win conditions don't seem to work.

The Upset challenge is meant to be played with tools that allow doing things like save states and frame perfect inputs. Alternatively, using another program to read (but not write to) the game's memory would be allowed.

If you watch enough tool-assisted speedruns (TAS), you will notice how people can manipulate luck in ways that an unassisted player is usually not able to do so. Try watching the TAS of Dragon Warrior for an example.

Here's a different non-win condition that might be interesting (and involves playing rationally):

Arena master:
In the Arena, kill the strongest monster that can be sent at you. (This is likely a Ravager.) Better yet, kill the maximum number of them that can be sent at you. Alternatively, kill enough monsters that the Monster Trainer runs out (if that is even possible).
For added challenge, limit your number of trips into the Arena (yelling at the announcer doesn't count as an extra trip) or limit the number of rests allowed. (How few rests can you accomplish this feat?)

I'm just really not on-board with trainers or tools outside of what the game provides. If it were a mod, that's one thing, but messing with the computer program itself isn't in scope here. These are simple challenges anyone can employ.

I'm also unskilled with such programs and wouldn't be able to offer any advice, test the challenge, or develop on the challenges. It doesn't appeal to me, but I could see a new thread being appropriate for players into that sort of thing.

There's a way to trigger a nasty spawn in the arena by backtalking to the announcer ("I spit in the face of Tectuktitlay himself!"). This is available after battling the mountain stalker and sligs. Seems like an appropriate challenge, good idea.

Rampager is the hardest creature in the game, bar none. Largely because of its resistances.

I'll attach a screen of a spawn I couldn't beat so you can see what I mean.

Added Defiant and Elemental.

Defiant Mortal is like a minigame itself... you could level your team all the way up in the arena in preparation for it and still fail. (See the screenshot above if you don't believe me) It all depends on what he spawns, sometimes it's mastyrials, sometimes stalkers, but once in awhile a horde of rampagers. D:

I'm definitely doing this on my next playthrough.