Stensia
From March of the Machine Commander set
Stensia
Plane — Innistrad
Whenever a creature deals damage to one or more players for the first time each turn, put a +1/+1 counter on it.
Whenever chaos ensues, each creature you control gains " : This creature deals 1 damage to target player or planeswalker" until end of turn.
Rulings
- Each creature can have only one +1/+1 counter put on it this way per turn.
- Unlike the Vampires in the Innistrad(TM) block, Stensia's ability triggers whenever a creature deals any damage, not just combat damage.