Critical strike

From Wikihack

Critical strike is a Technique a Rogue gets on 1st level in SLASH'EM.

It enables you to make one powerful attack against a single visible target. If the monster is not humanoid you deal (MONHP/4) + TECHLEVEL damage. Otherwise you deal (MONHP/2) + TECHLEVEL damage.

The technique is reusable after 500-1000 turns.