Grimgrin, Corpse-Born, and Zameck Guildmage

Prerequisites

• Grimgrin, Corpse-Born on the battlefield
• Zameck Guildmage on the battlefield
• available

Steps

1. Activate Zameck Guildmage's first ability by paying , causing your creatures to enter with an additional +1/+1 counter this turn
2. Activate Grimgrin by sacrificing the persist creature
3. When the persist creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it and at least one +1/+1 counter on it due to Zameck Guildmage
4. Remove a -1/-1 counter and a +1/+1 counter from that creature as a state-based action
5. Resolve the Grimgrin ability
6. Repeat from step 2

Results

• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers