Adarkar Valkyrie + Intruder Alarm + Progenitor Mimic

Adarkar Valkyrie

Intruder Alarm

Progenitor Mimic

How it works

1. Activate Adarkar Valkyrie by tapping it, targeting any legendary creature you control.
2. Cast Progenitor Mimic by paying 4, choosing to have it enter the battlefield as a copy of the legendary creature targeted in step 1.
3. Put the legendary creature into your graveyard due to the legend rule.
4. Adarkar Valkyrie and Intruder Alarm trigger.
5. Resolve the Intruder Alarm trigger, untapping all creatures.
6. Holding priority, activate Adarkar Valkyrie by tapping it, targeting Progenitor Mimic.
7. Resolve the Adarkar Valkyrie trigger from step 4, returning the legendary creature to the battlefield from your graveyard.
8. Put Progenitor Mimic into your graveyard due to the legend rule.
9. Adarkar Valkyrie and Intruder Alarm trigger.
10. Resolve the Intruder Alarm trigger, untapping all creatures.
11. Holding priority, activate Adarkar Valkyrie by tapping it, targeting the legendary creature.
12. Resolve the Adarkar Valkyrie trigger from step 9, returning Progenitor Mimic to the battlefield from your graveyard as a copy of the legendary creature.
13. Repeat from step 3.

This elegant loop relies on the constant tension of the legend rule to repeatedly trigger death and entry effects, all fueled by the clever placement of Adarkar Valkyrie. By having Progenitor Mimic enter as a copy of a legendary creature you already control, state-based actions force one into the graveyard—which in turn triggers Adarkar Valkyrie's delayed return ability. Meanwhile, Intruder Alarm acts as the mechanical heart of the engine, using every new creature entry to untap Adarkar Valkyrie and keep the cycle spinning infinitely.