Mephidross Vampire + Triskelion

Mephidross Vampire
Triskelion

Requires
All permanents on the battlefield. Triskelion has at least one +1/+1 counter on it.
Steps
  1. Activate Triskelion by removing a +1/+1 counter from it, dealing 1 damage to any creature an opponent controls
  2. Triskelion triggers, putting a +1/+1 counter on itself
  3. Repeat as desired
  4. You may also repeat this loop whenever a creature enters the battlefield under an opponent's control
Results
Infinite damage to creatures. Destroy any number of creatures opponents control. Destroy all creatures that enter the battlefield under an opponent's control