Ordeal of Heliod
Enchantment — Aura
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, you gain 10 life.
Lucas Graciano
Masters 25 (A25)
• #27Rulings
If you sacrifice the Ordeal in some other way, its last ability will trigger.
(wotc • 2013-09-15)
The +1/+1 counter is put on the creature before blockers are declared and before combat damage is dealt.
(wotc • 2013-09-15)
The check of whether the enchanted creature has three or more +1/+1 counters on it happens as part of the resolution of the attack triggered ability. If the third +1/+1 counter is put on the enchanted creature any other way, you won't sacrifice the Ordeal until the next time the creature attacks.
(wotc • 2013-09-15)
Rulings
If you sacrifice the Ordeal in some other way, its last ability will trigger.
(wotc • 2013-09-15)
The +1/+1 counter is put on the creature before blockers are declared and before combat damage is dealt.
(wotc • 2013-09-15)
The check of whether the enchanted creature has three or more +1/+1 counters on it happens as part of the resolution of the attack triggered ability. If the third +1/+1 counter is put on the enchanted creature any other way, you won't sacrifice the Ordeal until the next time the creature attacks.
(wotc • 2013-09-15)