Deathbringer Thoctar + Basilisk Collar

Deathbringer Thoctar
Basilisk Collar

Requires
Deathbringer Thoctar must be on the battlefield. Basilisk Collar must be on the battlefield. Deathbringer Thoctar has at least one +1/+1 counter on it. Basilisk Collar attached to Deathbringer Thoctar.
Steps
  1. Activate Deathbringer Thoctar by removing a +1/+1 counter from it, dealing 1 damage to any creature an opponent controls and causing you to gain 1 life.
  2. The creature dies as a state-based action due to Deathbringer Thoctar's deathtouch.
  3. Deathbringer Thoctar triggers, putting a +1/+1 counter on itself.
  4. Repeat as desired.
  5. You may also repeat this combo whenever a creature enters the battlefield under an opponent's control.
Results
Destroy all creatures opponents control. Destroy any creature that enters the battlefield under an opponent's control.