Roar of the Kha in exile (Roar of the Kha exiled by Isochron Scepter).
Isochron Scepter and Xenic Poltergeist on the battlefield.
You control creatures that can tap to produce at least ({3} magic symbol) .
Xenic Poltergeist does not have summoning sickness.
({1} magic symbol) available.
Steps
Activate Xenic Poltergeist's first ability by paying ({1} magic symbol) and tapping it, causing Isochron Scepter to become an artifact creature until your next upkeep.
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.