Altar of Dementia + Dualcaster Mage + Behold the Sinister Six!

Altar of Dementia

Dualcaster Mage

Behold the Sinister Six!

How it works

1. Cast Behold the Sinister Six! by paying its mana cost
2. Holding priority, cast Dualcaster Mage by paying its mana cost.
3. When Dualcaster Mage enters, it triggers, targeting Behold the Sinister Six!.
4. Holding priority, activate Altar of Dementia by sacrificing Dualcaster Mage.
5. Resolve the Dualcaster Mage trigger, copying Behold the Sinister Six!, with the copy targeting Dualcaster Mage
6. Resolve the Behold the Sinister Six! copy, returning Dualcaster Mage from your graveyard to the battlefield.
7. Repeat from step 3.

This clever loop achieves infinite self-mill and sacrifice triggers by utilizing Behold the Sinister Six! to endlessly pull Dualcaster Mage right back out of the graveyard. Once Altar of Dementia is on the battlefield to serve as your sacrifice outlet, you cast the spell and flash in the Mage to copy it, targeting the original spell still on the stack. Sacrificing the Mage to the Altar mills your opponent before the copy resolves to return the Mage to the battlefield, restarting the cycle and letting you repeat the process indefinitely.