This is inspired by one of the rooms in Kelsey Dionne’s “The Lost Citadel” Shadowdark adventure.

In a large temple sanctuary, a large statue of the bull god Minoros sits. On the walls, painted depictions of worshipers show them making blood sacrifices to the god. An inscription in Blacktongue (the common language of many dark creatures) says that a blood sacrifice will be welcomed by Minoros, who will grant a boon.

Make a full blood sacrifice in the name of the great Minoros, and yea, he shall grant thee a boon in his pleasure.

The party’s cleric knows this means that if you kill a warm-blooded creature (of 1 hit die or more) in the bull god’s name (literally just shout “for Minoros” or something in combat), you can gain a boon. Roll 1d3, but on each successive sacrifice gain a cumulative +1…

1. +1 dexterity, and you become slightly more lean and lithe.
2. +1 constitution, and you become slightly grizzled looking.
3. +1 strength, and you become slightly hairier.
4. -1 charisma, and you become slightly more fierce in temperament.
5. -1 wisdom, and you grow a bull’s tail.
6. -1 intelligence, and you grow small horns.
7. or more. You transform entirely into a minotaur and become an NPC.

If a character devoted to another god (cleric, druid, paladin, etc.) makes a sacrifice to Minoros, their god will very likely punish the character by stripping away their powers until they atone for the transgression.