I was just playing around and experimenting a bit. Gave my main character (Paladin) potion against petrification and that death ward thingie, blessing - and then ran up to Saverok, then back to my main party.
Then all hell broke loose - and despite me being just about to lose the fight, it all ended because I managed to kill off Sarevok. Grmpf. I just feel like having accidentally cheated, lol.
But well, yeah. If I had prepared my party additionally against "Chaos" I might have had a chance to win fairly.
You can always replay it if you want :)
Protection from Evil and Bless are two spells I almost always use to buff the party, and they should help a little. Defensive Harmony is short-lasting, but it helps. Then you have potions that increase saving throws by five, and many other things. For the really big fights, usually some of my character mini-pictures (to the right) are just about filled up with buffing icons :D
Why did the BGT developers give that character that spell anyway? Maybe they thought the game was too fair (even with an enemy capable of casting Improved Invisibility that a 1st level party could reasonably encounter), so they decided to make it less fair.
In any case, if you want to get revenge on the game, you could cheat the Greater Deathblow skill onto a character and fire Arrows of Detonation with that skill active; that kills everything level 12 or under in the affected area. That ability is generally considered underpowered in Throne of Bhaal, where it originates; it is ludicrously overpowered in Baldur's Gate 1, which was certainly *not* designed with that skill in mind. (You might want to remove the skill afterward or just not use that character or save file.)
As a side note, the tutorial guy in the Baldur's Gate 2 tutorial (which might not be playable in a BGT installation; I haven't tried BGT myself), who is clearly meant to be unkillable, can be killed with Greater Deathblow. (This will, of course, softlock the game because there's no way to continue with him dead.)
Don't understand why you keep mentioning different ways to cheat, but whatever floats your boat. If people want to cheat they may as well just use Ctrl-Y (or whatever it is) to insta-kill enemies. Makes everything pointless, but if you want to cheat, may as well go the whole nine yards.
Think it was a mistake to put Death Spell into the BGT final fight. Very few characters will be able to withstand that as they're unlikely to be level 9 or above. The fight itself is difficult enough without hitting you with almost impossible to defend against instadeath.
Unlike in the Tutu playthrough, where everybody got engaged when Sarevok did, this didn't appear to happen in BGT, so it would have been better to fix that rather than throw Death Spell at us.