Spawning Pit + Dualcaster Mage + Leonardo's Technique

Spawning Pit

Dualcaster Mage

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 Spawning Pit 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 recursive loop leverages Dualcaster Mage entering the battlefield to endlessly copy Leonardo's Technique, which continuously pulls the Mage right back out of your graveyard. To keep the engine looping smoothly, Spawning Pit provides a vital sacrifice outlet that sends the Mage back to the graveyard while stacking up charge counters on the artifact.