Enchantment — Aura Curse, 1R (2)
Rare
Enchant player
Whenever a creature deals combat damage to enchanted player, put a +1/+1 counter on that creature.
"Innocent thorns can fill the air with your bloodscent. Don't stray from the path."
—Elmut, crossway watcher
Illus. Christopher Moeller

9/22/2011: The ability will trigger when any creature deals combat damage to the enchanted player, including one controlled by another opponent or even by the enchanted player (if combat damage gets redirected somehow).
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Extended (Type 1.X)
Legal in Standard (Type 2)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern