Mikaeus, the Unhallowed + Viscera Seer + Thunderblust

Mikaeus, the Unhallowed

Viscera Seer

Thunderblust

How it works

1. Activate Viscera Seer by sacrificing Thunderblust.
2. When Thunderblust dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Viscera Seer ability.
4. Activate Viscera Seer by sacrificing Thunderblust.
5. When Thunderblust dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Resolve the Viscera Seer ability.
7. Repeat.

This elegant loop relies on a clever mechanical interaction between Mikaeus, the Unhallowed and Thunderblust, using their opposing counter abilities to keep the cycle going indefinitely. Whenever you sacrifice Thunderblust to Viscera Seer, its native persist ability brings it back with a -1/-1 counter; however, Mikaeus, the Unhallowed grants it undying, allowing it to return with a +1/+1 counter the next time it dies because state-based actions cancel out the counters. This perpetual motion machine lets you churn through your library with infinite scry triggers while generating an endless stream of sacrifices, leaves-the-battlefield, and enters-the-battlefield events.