Urza, Lord High Artificer, Corridor Monitor, Retraction Helix, and Rakdos, Lord of Riots

Prerequisites

• Urza, Lord High Artificer on the battlefield
• Corridor Monitor in hand
• Retraction Helix in hand
• Rakdos, Lord of Riots on the battlefield
• available

Steps

1. Cast Retraction Helix by paying , targeting a creature you control that doesn't have summoning sickness
2. Cast Corridor Monitor by paying due to Rakdos
3. When Corridor Monitor enters, it triggers, untapping the creature targeted by Retraction Helix
4. Activate Urza's first ability by tapping Corridor Monitor, adding
5. Activate the creature targeted by Retraction Helix by tapping it, returning Corridor Monitor from the battlefield to your hand
6. Repeat from step 2

Results

• Infinite ETB
• Infinite LTB
• Infinite storm count