Putrid Goblin + Goblin Trashmaster + Cayth, Famed Mechanist

Putrid Goblin

Goblin Trashmaster

Cayth, Famed Mechanist

How it works

1. Activate Goblin Trashmaster by sacrificing Putrid Goblin
2. When Putrid Goblin dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Putrid Goblin enters, its fabricate ability triggers, putting a +1/+1 counter on it.
4. Resolve the Goblin Trashmaster ability.
5. Repeat.