Mikaeus, the Unhallowed + Woe Strider + Grim Poppet

Mikaeus, the Unhallowed

Woe Strider

Grim Poppet

How it works

1. Activate Woe Strider by sacrificing Grim Poppet.
2. When Grim Poppet dies, its undying ability triggers, returning it from your graveyard to the battlefield without a +1/+1 counter on it due to its replacement effect.
3. Resolve the Woe Strider ability
4. Repeat.

This loop turns a clever piece of counter-mitigation into an endless engine of sacrifice and rebirth. With Mikaeus, the Unhallowed granting its passive undying bonus to non-Humans, every time Woe Strider devours Grim Poppet, the Poppet's undying triggers to bring it right back to the battlefield. Because Grim Poppet enters with its own -1/-1 counters, you can simply use its activated ability to remove those counters from itself, ensuring it never accumulates the +1/+1 counters that would otherwise permanently shut off its undying revival.