Urza, Lord High Artificer, Sewer-veillance Cam, and Retraction Helix

Prerequisites

• Urza, Lord High Artificer on the battlefield
• Sewer-veillance Cam in hand
• Retraction Helix in hand
• available

Steps

1. Cast Retraction Helix by paying , targeting a creature you control that doesn't have summoning sickness
2. Cast Sewer-veillance Cam by paying
3. When Sewer-veillance Cam enters, it triggers, untapping a creature you control
4. Activate Urza's first ability by tapping Sewer-veillance Cam, adding
5. Activate the creature targeted by Retraction Helix by tapping it, returning Sewer-veillance Cam from the battlefield to your hand
6. When Sewer-veillance Cam leaves the battlefield, it triggers, untapping the creature tapped in step 5
7. Repeat

Results

• Cast all spells in your library
• Exile your library
• Infinite blue mana
• Infinite mana creatures you control can produce
• Infinite storm count
• Infinite untap of creatures you control