Dual Casting, Intruder Alarm, and Deekah, Fractal Theorist

Prerequisites

• Dual Casting on the battlefield
• Intruder Alarm on the battlefield
• Deekah, Fractal Theorist on the battlefield
• Dual Casting attached to a creature without summoning sickness
• You have an instant or sorcery card in hand with enough mana to cast it
• Creatures you control can tap to produce at least

Steps

1. Cast any instant or sorcery by paying its mana cost
2. Deekah triggers, creating a 0/0 Fractal creature token and putting a number of +1/+1 counters on it equal to the spell's mana value
3. The Fractal enters the battlefield, triggering Intruder Alarm, untapping all creatures
4. Activate all mana-producing creatures you control by tapping them, adding at least
5. Activate the creature with Dual Casting attached by paying and tapping it, copying the instant or sorcery spell you cast
6. Repeat from step 2

Results

• Infinite copies of any instants and/or sorceries you cast
• Infinite creature tokens
• Infinite ETB
• Infinite magecraft triggers
• Infinite mana creatures you control can produce
• Infinite untap of all creatures