Vraska, Swarm's Eminence + Walking Ballista

Vraska, Swarm's Eminence
Walking Ballista

Requires
Vraska, Swarm's Eminence must be on the battlefield. Walking Ballista must be on the battlefield. Walking Ballista has at least two +1/+1 counters. You have a way to give Walking Ballista deathtouch.
Steps
  1. Give Walking Ballista deathtouch.
  2. Activate Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 1 damage to an opponent.
  3. Vraska triggers, putting a +1/+1 counter on Walking Ballista.
  4. Repeat steps 2-3.
Results
Infinite damage.