Celes, Rune Knight, and Grimgrin, Corpse-Born

Prerequisites

• Celes, Rune Knight on the battlefield
• Grimgrin, Corpse-Born on the battlefield

Steps

1. Activate Grimgrin by sacrificing the persist creature
2. When the persist creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. When the persist creature enters the battlefield, Celes's second ability triggers, putting a +1/+1 counter on each creature you control
4. Resolve the Grimgrin ability
5. Repeat

Results

• Infinite +1/+1 counters on creatures you control
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers