Putrid Goblin, Goblin Trashmaster, and Cayth, Famed Mechanist

Prerequisites

• Putrid Goblin on the battlefield
• Goblin Trashmaster on the battlefield
• Cayth, Famed Mechanist on the battlefield

Steps

1. Activate Goblin Trashmaster 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, its fabricate ability triggers, putting a +1/+1 counter on it
3. Resolve the Goblin Trashmaster ability
4. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers