Discordant Spirit

{2}{B}{R}Creature — Spirit2/2

At the beginning of each end step, if it's an opponent's turn, put a +1/+1 counter on this creature for each 1 damage dealt to you this turn.

At the beginning of your end step, remove all +1/+1 counters from this creature.

This will not count damage that was prevented. (2004-10-04)
In Two-Headed Giant, triggers only once per end of turn, not once for each player. (2006-05-01)

Cards like this

Functionally similar cards by meaning — playable in Discordant Spirit’s colours.