[Wereboar]

Originally posted by Marathon: However, I'm playing through with a Bishop in my party for the first time in years, and really want to see if I can make him more of a killing machine.

You wont't. If you have one pure spellcaster in a party, he'll always be the supporter (at least after say level 10).

What are considered the best damage spells (not instant kill spells, but actual damage) that come in handy through the end game?

Fire spells (lightning, fire bomb, boiling blood, nuclear blast) are best in general. But there are several exception: Rapax area, underwater areas, 1/4 of ascension peak (the chaos route).
Frost spells (Blizzard, Tsunami) work best in Rapax areas, and in the chaos route on ascension peak
Mental spells (psionic blast, mind flail, concussion) are great against anything that casts elemental shield.
Earth spells (earth quake, falling stars) are some all-purpose spells, and are the best availavle in the underwater areas.
Divinity has lifesteal and might to magic. I've done fights at ascension peak with these spells alone, for example against death wings or scorchers, and didn't run out of spell points.
Air is the worst realm for pure damage, although toxic cloud has nice status effects.

Secondarily, what instant kill spells do you favor?

None.
If i have several pure spellcasters, instant kill spells are useless. They remove some of the enemies, but you don't need less spell power to kill the remaining ones. Only instant kill spell i use is eye for an eye.

Lastly, what are the best spells to use to build a Bishop toward a higher alchemy skill?

You need an alchemy spell that isn't also in Wizardry. I think you have to stick to acid splash and the like until you reach alchemy 45, then you can learn fire bomb and acid bomb.

Again: Don't try to make your lone bishop to a killing maching. Better use him for support in this party, and start a spallcaster party later.

Just yesterday, i just finished a spell heavy game. Mage, Psionic, Priest, Alchemist, Bishop, and Bard. Bard is nice in such a group since he can work as a tank and do melee damage if necessary (there is a handful of monsters that are very resistant to magic). But he can use instruments as his primary weapons, and thus fits nicely in a magic heavy group. BTW the bishop was by far the most useless character in the party, since he has trouble getting his spell skills beyond 75.