Pit Fiend

Pit Fiends are powerful devils encountered in-game or summoned by the Gate spell. They are immune to +2 weapons or lower, regenerate 3HP/round, and attack with 3d4 claws as well as cast three clerical spells: Miscast Magic, Lightning Bolt and Cause Critical Wounds.

They are generally considered the strongest standard(ie. not summoned via High-Level Abilities) summons in the game.

Special characteristics:
-Immunity to 2+ weapons or lower

-Regeneration 3HP/round