Adarkar Valkyrie + Intruder Alarm + Undercover Operative

Adarkar Valkyrie

Intruder Alarm

Undercover Operative

How it works

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

This fascinating loop turns the classic legend rule into an engine, using Undercover Operative to repeatedly copy a legendary creature while Adarkar Valkyrie continuously resurrects whichever half of the pair just hit the graveyard. The presence of Intruder Alarm is the secret to sustaining this dance, as every single entry of a cloned legendary creature triggers the enchantment to untap Adarkar Valkyrie so she can tap again and keep the cycle moving.