Isochron Scepter + Vitalize + Karn's Touch

Isochron Scepter

Vitalize

Karn's Touch

How it works

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