Greven, Predator Captain + Necropotence

Greven, Predator Captain
Necropotence

Requires
Greven, Predator Captain must be on the battlefield. Necropotence must be on the battlefield. Greven does not have summoning sickness and cannot be blocked by an opponent.Your life total is at least 17.
Steps
  1. Activate Necropotence by paying 1 life, exiling the top card of your library and giving Greven +1/+1 until end of turn due to its first ability.
  2. Repeat step 1 until Greven is a 21/21 creature.
  3. Deal combat damage to an opponent using Greven.
  4. The opponent loses the game due to being dealt 21 combat damage from your commander.
Results
Target opponent loses the game.