Gandalf the White, Gonti's Aether Heart, Prototype Portal, and Lithoform Engine

Prerequisites

• Gandalf the White on the battlefield
• Gonti's Aether Heart in exile
• Prototype Portal on the battlefield
• Lithoform Engine on the battlefield
• each turn available

Steps

1. Activate Prototype Portal by paying and tapping it
2. Holding priority, activate Lithoform Engine's first ability by paying and tapping it, copying Prototype Portal's ability
3. Resolve the copy of Prototype Portal's ability, creating a token copy of Gonti's Aether Heart
4. When the Gonti's Aether Heart token enters the battlefield, it triggers twice, causing you to get
5. Resolve the original Prototype Portal ability, creating a token copy of Gonti's Aether Heart
6. Put either Gonti's Aether Heart token into your graveyard due to the legend rule
7. When the Gonti's Aether Heart token enters the battlefield, it triggers twice, causing you to get
8. Activate the remaining Gonti's Aether Heart token by paying eight and exiling it, causing you to take an extra turn after this one
9. Repeat each turn

Results

• Infinite turns