Roar of the Kha in exile (Roar of the Kha exiled by Isochron Scepter).
Isochron Scepter and Toymaker on the battlefield.
You control creatures that can tap to produce at least ({3} magic symbol) .
You have at least one card in hand.
Toymaker does not have summoning sickness.
({1} magic symbol) available.
Steps
Activate Toymaker's first ability by paying ({1} magic symbol) , tapping it and discarding a card, causing Isochron Scepter to become an artifact creature until end of turn.
Activate creatures you control by tapping those, adding ({3} magic symbol) .
Activate Isochron Scepter by paying ({2} magic symbol) and tapping it, casting a copy of Roar of the Kha without paying its mana cost, untapping all creatures.