Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Intruder Alarm, and Sparkcaster

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Intruder Alarm on the battlefield
• Sparkcaster in hand

Steps

1. Cast Sparkcaster by paying its mana cost reduced by the number of creatures you can tap while casting it
2. When Sparkcaster enters, its first and second abilities and Intruder Alarm trigger
3. Resolve the second Sparkcaster trigger, dealing 1 damage to target player or planeswalker Resolve the first Sparkcaster trigger, returning it from the battlefield to your hand
4. Resolve the Intruder Alarm trigger, untapping all creatures
5. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite damage
• Infinite storm count
• Infinite mana creatures you control can produce
• Infinite untap of creatures