Mikaeus, the Unhallowed + Soulstinger + Umbral Collar Zealot

Mikaeus, the Unhallowed

Soulstinger

Umbral Collar Zealot

How it works

1. Activate Umbral Collar Zealot 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 Umbral Collar Zealot ability
5. Repeat.

This elegant loop turns Mikaeus, the Unhallowed into a relentless engine of recycling by granting undying to your other non-Human creatures. When you sacrifice Soulstinger to Umbral Collar Zealot, Mikaeus brings it right back to the battlefield with a +1/+1 counter. Because Soulstinger's own enters-the-battlefield trigger forces you to place two -1/-1 counters on a creature you control, you can target Soulstinger itself; these -1/-1 counters immediately annihilate the +1/+1 counter from undying, leaving the insect clean and ready to repeat the cycle indefinitely.