Putrid Goblin + First Day of Class + Carrion Feeder

Putrid Goblin

First Day of Class

Carrion Feeder

How it works

1. Cast First Day of Class by paying 1, causing all creatures that enter the battlefield under your control this turn to get an additional +1/+1 counter put on it.
2. Activate Carrion Feeder by sacrificing Putrid Goblin.
3. Putrid Goblin's persist ability triggers, returning itself from your graveyard to the battlefield with a -1/-1 counter on it.
4. Putrid Goblin enters the battlefield, triggering First Day of Class, putting a +1/+1 counter on Putrid Goblin.
5. Resolve the Carrion Feeder ability from step 2, putting a +1/+1 counter on it.
6. Repeat from step 2.