Ertha Jo, Frontier Mentor + Clock of Omens + Kragma Butcher + Encroaching Mycosynth

Ertha Jo, Frontier Mentor

Clock of Omens

Kragma Butcher

Encroaching Mycosynth

How it works

1. Activate Clock of Omens by tapping it and Kragma Butcher, targeting Kragma Butcher.
2. Ertha Jo triggers, copying Clock of Omens' ability, targeting Clock of Omens.
3. Resolve both Clock of Omens abilities, untapping it and Kragma Butcher.
4. Kragma Butcher triggers, giving it +2/+0 until end of turn.
5. Repeat.

This loop relies on Ertha Jo, Frontier Mentor turning a standard untap engine into an explosive power-generator by doubling every activation that targets a creature or player. Normally, Clock of Omens requires two untapped artifacts to untap just one, but Ertha Jo's reflexive copying duplicates the ability so that one activation cleanly untaps both the Clock and the creature you tapped. Crucially, Encroaching Mycosynth weaves the whole engine together by making every nonland permanent you control—including Ertha Jo and Kragma Butcher—an artifact, ensuring you always have eligible targets for the Clock. As you loop this process endlessly, the repeated untapping triggers Kragma Butcher's inspired ability over and over, stacking up an arbitrarily large power boost until end of turn.