Ashnod's Altar, Dualcaster Mage, and Extract from Darkness

Prerequisites

• Ashnod's Altar on the battlefield
• Dualcaster Mage in hand
• Extract from Darkness in hand
• available

Steps

1. Cast Extract from Darkness by paying its mana cost Holding priority, cast Dualcaster Mage by paying its mana cost
2. When Dualcaster Mage enters, it triggers, targeting Extract from Darkness
3. Holding priority, activate Ashnod's Altar by sacrificing Dualcaster Mage
4. Resolve the Dualcaster Mage trigger, copying Extract from Darkness Resolve the Extract from Darkness copy, causing each player to mill two cards and returning Dualcaster Mage from your graveyard to the battlefield
5. Repeat from step 3

Results

• Infinite colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite magecraft triggers
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill