Critical Strike is overpowered - on dungeon level 23, with a 111 damage weapon and Strength 200, Intelect 42 I'm killing in one critical hit anything - including bosses
I find that Critical Strike is the most useful spell for a fighter-oriented character (and with the life steal of the vampires, makes for great survivability in later levels (floor 14 and later). I died easily with no elemental protection, but now with elemental protection at about 60 or so it's a breeze (dungeon level 22)
 "Clockwords: Prelude"){kind=icon}
 "Idle Mine"){kind=icon}
 "Hack Slash Crawl"){kind=icon}