Infinite +1/+1 counters on a creatureInfinite damageInfinite lifegainInfinite lifegain triggers
How it works
Activate Christine Chapel by using Walking Ballista's ability by removing a +1/+1 counter from it, dealing 1 damage to any target and causing you to gain 1 life due to its lifelink.
Christine Chapel triggers, putting two +1/+1 counters on it.