Altar of Sacrifice
Altar of Sacrifice is an adventure map location, that has a function that differs based on the hero's alignment. Castle, Tower and Rampart heroes, who are considered to be good alignment, can only sacrifice artifacts on the altar for experience. Inferno, Necropolis and Dungeon heroes, who are considered to be evil alignment, can only sacrifice creatures on the altar. Heroes from neutral alignment factions Stronghold, Fortress and Conflux can sacrifice either artifacts or creatures.
The amount of experience gained from the sacrifice depends on either on the artifact class or creature level. Peasants provide no experience, and you cannot sacrifice them unless something else is also on the altar.