Death Strike is by far the toughest non-broken spell in the game that I can find. From my tests, I found that it consistently does 200 hp damage. That is enough to kill any of the enemy characters in one hit!
Mystic Arrow did around 10 hp damage most times, but I observed it doing anywhere from 10-25 damage.
Fireball did somewhere in the range of 20 to 40 in the few tests I did with it. I did not test the splash damage of Fireball, so I don't know if it does full damage or a reduction of the original damage.
I did not get around to testing Lightning yet, but I always thought it did more damage than Mystic Arrow and less than Fireball. Anyone know about this?
Also worth mentioning is that I tested on my own character with no immunities or resistances. Most enemy characters have at least some sort of resistance, as detailed in Gandreas' list of monsters here.
I'm certain immunities negate all related damage, but I wonder to what degree the resistances work. Are they static (such as 5 hp damage negated) or are they some percentage based on total damage (for instance, 25% of total damage removed)? I'm sure that only Gandreas can answer these questions, so we may never know the answers.
Back on topic, has anyone done their own tests with spell damage? What have you found to be the most useful spell in combat?
This post has been edited by The Wizard: 11 January 2011 - 06:32 PM