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
2. Holding priority, cast Dualcaster Mage by paying
3. When Dualcaster Mage enters the battlefield, it triggers, copying Extract from Darkness
4. Activate Ashnod's Altar by sacrificing Dualcaster Mage, adding
5. Resolve the copy of Extract from Darkness, causing each player to mill two cards, and you to return Dualcaster Mage from your graveyard to the battlefield
6. 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
• Put all creature and planeswalker cards from each opponent's library and graveyard onto the battlefield under your control