Vesperlark + Activated Sleeper + Carrion Feeder

Vesperlark

Activated Sleeper

Carrion Feeder

How it works

1. Activate Carrion Feeder by sacrificing Vesperlark.
2. When Vesperlark dies, it triggers, returning Activated Sleeper from your graveyard to the battlefield as a copy of Vesperlark.
3. Activate Carrion Feeder by sacrificing Activated Sleeper.
4. When Activated Sleeper dies, it triggers, returning Activated Sleeper from your graveyard to the battlefield as a copy of Vesperlark.
5. Resolve the Carrion Feeder ability, putting a +1/+1 counter on it.
6. Repeat from step 3.

This elegant loop turns Vesperlark and Activated Sleeper into a self-sustaining cycle of recursion, fueled entirely by the sacrifice outlet Carrion Feeder. When Vesperlark is sacrificed, its leaves-the-battlefield trigger pulls Activated Sleeper from the graveyard, allowing it to enter as a fresh copy of Vesperlark. Because this copy then dies to Carrion Feeder, its own death trigger brings back another copy of Activated Sleeper, infinitely repeating the process to grow Carrion Feeder into an infinitely massive threat while triggering endless deaths and enters-the-battlefield effects.