Dualcaster Mage + Bloodthrone Vampire + Leonardo's Technique

Dualcaster Mage

Bloodthrone Vampire

Leonardo's Technique

How it works

1. Cast Leonardo's Technique by paying its mana cost, targeting any applicable target.
2. Holding priority, cast Dualcaster Mage by paying its mana cost.
3. When Dualcaster Mage enters, it triggers, targeting Leonardo's Technique.
4. Holding priority, activate Bloodthrone Vampire by sacrificing Dualcaster Mage.
5. Resolve the Dualcaster Mage trigger, copying Leonardo's Technique, with the copy targeting Dualcaster Mage
6. Resolve the Leonardo's Technique copy, returning Dualcaster Mage from your graveyard to the battlefield.
7. Repeat from step 3.

This clever loop sets up an infinite recursion engine by leveraging Leonardo's Technique to continuously pull creatures right back out of the graveyard. When you cast Dualcaster Mage, its enter-the-battlefield trigger copies the spell targeting the Mage itself, creating an unending chain of copies and resolutions. To keep the loop from fizzling and to fuel the cycle anew, Bloodthrone Vampire stands ready to sacrifice the Mage in response, sending it back to the graveyard just in time to be resurrected by the next copy.