Bartolomé del Presidio, Return to Action, and Dualcaster Mage

Prerequisites

• Bartolomé del Presidio on the battlefield
• Return to Action in hand
• Dualcaster Mage in hand
• available

Steps

1. Cast Return to Action by paying its mana cost
2. Holding priority, cast Dualcaster Mage by paying its mana cost
3. When Dualcaster Mage enters, it triggers, copying Return to Action, with the copy targeting Dualcaster Mage
4. Resolve the copy of Return to Action
5. Holding priority, activate Bartolomé del Presidio by sacrificing Dualcaster Mage
6. When Dualcaster Mage dies, it triggers, returning it from your graveyard to the battlefield
7. Repeat from step 3
8. Resolve all Bartolomé del Presidio abilities from step 5

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite magecraft triggers
• Infinite +1/+1 counters on Bartolomé del Presidio