Adarkar Valkyrie + Intruder Alarm + Vesuvan Doppelganger

Adarkar Valkyrie

Intruder Alarm

Vesuvan Doppelganger

How it works

1. Activate Adarkar Valkyrie by tapping it, targeting any legendary creature you control.
2. Cast Vesuvan Doppelganger by paying 3, 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 Vesuvan Doppelganger.
7. Resolve the Adarkar Valkyrie trigger from step 4, returning the legendary creature to the battlefield from your graveyard.
8. Put Vesuvan Doppelganger 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 Vesuvan Doppelganger to the battlefield from your graveyard as a copy of the legendary creature.
13. Repeat from step 3.

This fascinating loop lets you continuously cycle through a legendary creature and Vesuvan Doppelganger by leveraging the legend rule to repeatedly send them to the graveyard. While Adarkar Valkyrie provides the delayed resurrection trigger to bring each piece back to the battlefield in turn, Intruder Alarm ties the whole engine together with its passive ability, automatically untapping your creatures—including the Valkyrie—whenever a creature enters. As long as you have a target for the Valkyrie's tap ability, this creates an endless back-and-forth cycle of deaths and entries that fuels infinite triggers and untaps.