Isochron Scepter + Roar of the Kha + Tezzeret, Agent of Bolas

Isochron Scepter

Roar of the Kha

Tezzeret, Agent of Bolas

How it works

1. Activate Tezzeret's second loyalty ability by removing 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.
3. Activate Isochron Scepter by paying 2 and tapping it, casting a copy of Roar of the Kha without paying its mana cost, untapping all creatures.
4. Repeat from step 2.