Putrid Goblin, Cathars' Crusade, and Goblin Chirurgeon

Prerequisites

• Putrid Goblin on the battlefield
• Cathars' Crusade on the battlefield
• Goblin Chirurgeon on the battlefield

Steps

1. Activate Goblin Chirurgeon by sacrificing Putrid Goblin When Putrid Goblin dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
2. When Putrid Goblin enters, Cathars' Crusade triggers, putting a +1/+1 counter on each creature you control Resolve the Goblin Chirurgeon ability
3. Repeat

Results

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