Agatha's Soul Cauldron + Grumgully, the Generous + Krenko, Mob Boss + Yarus, Roar of the Old Gods

Agatha's Soul Cauldron

Grumgully, the Generous

Krenko, Mob Boss

Yarus, Roar of the Old Gods

How it works

1. Activate a creature with a +1/+1 counter on it, creating a 1/1 red Goblin creature token.
2. The 1/1 Goblin token enters with a +1/+1 counter on it due to Grumgully's ability.
3. Repeat.