厄睿柏斯的试炼 (Ordeal of Erebos) (zhs)
Enchantment - Aura
(CMC 2)
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 Ordeal of Erebos.
When you sacrifice Ordeal of Erebos, target player discards two cards.