Miirym, Sentinel Wyrm + Bladewing the Risen + Pandemonium

Miirym, Sentinel Wyrm

Bladewing the Risen

Pandemonium

How it works

1. Cast Bladewing by paying 3.
2. When Bladewing enters the battlefield, it, Pandemonium and Miirym trigger.
3. Resolve the Bladewing trigger, returning any Dragon from your graveyard to the battlefield.
4. Resolve the Pandemonium, dealing 4 damage to Bladewing.
5. Bladewing dies as a state-based action due to having 0 toughness.
6. Resolve the Miirym trigger, creating a nonlegendary token copy of Bladewing.
7. When the Bladewing token enters the battlefield, it and Pandemonium trigger.
8. Resolve the Pandemonium trigger, dealing damage to any target.
9. Resolve the Bladewing token's trigger, returning Bladewing from your graveyard to the battlefield.
10. Repeat from step 2.

This loop turns the graveyard into a revolving door of draconic devastation, anchored entirely by Pandemonium to constantly trigger damage upon entry. Whenever Bladewing the Risen enters the battlefield, Miirym, Sentinel Wyrm steps in to duplicate it, creating a nonlegendary token copy that bypasses the legend rule. That token's own entry triggers a resurrection of the original Bladewing from the graveyard, while Pandemonium simultaneously uses the dragon's power to finish off the original Bladewing so it can be brought back over and over again.