Isochron Scepter, Vitalize, and Karn, the Great Creator

Prerequisites

• Isochron Scepter on the battlefield
• Vitalize in exile
• Karn, the Great Creator on the battlefield
• You control creatures that can tap to produce at least

Steps

1. Activate Karn's first loyalty ability by adding a loyalty counter on it, causing Isochron Scepter to become an artifact creature until end of turn
2. Activate creatures you control by tapping those, adding at least
3. Activate Isochron Scepter by paying and tapping it, casting a copy of Vitalize without paying its mana cost, untapping all creatures
4. Repeat from step 2

Results

• Infinite mana creatures you control can produce
• Infinite storm count