Ordeal of Purphoros - Theros - 131

Enchantment — Aura

Mana Cost: {1}{R}

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice this Aura.
When you sacrifice this Aura, it deals 3 damage to any target.

Uncommon · Theros · #131 (THS)

Illustrated by Maciej Kuciara