Mikaeus, the Unhallowed + Soulstinger + Carrion Feeder

Mikaeus, the Unhallowed

Soulstinger

Carrion Feeder

How it works

1. Activate Carrion Feeder by sacrificing Soulstinger.
2. When Soulstinger dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. When Soulstinger enters the battlefield, it triggers, putting a -1/-1 counter on it.
4. Resolve the Carrion Feeder ability
5. Repeat.

This clever loop relies on Mikaeus, the Unhallowed to grant undying to your non-Human creatures, turning every trip to the graveyard into a return ticket. When you sacrifice Soulstinger to Carrion Feeder, Mikaeus brings it right back with a +1/+1 counter, but Soulstinger's own enters-the-battlefield trigger immediately places two -1/-1 counters back onto it. State-based actions promptly see the +1/+1 counter and -1/-1 counter annihilate each other, leaving Soulstinger completely clean of counters and ready to repeat the entire cycle. Meanwhile, Carrion Feeder grows infinitely large with endless +1/+1 counters as it fuels this perpetual motion machine of sacrifices.