Energy Arc in exile (Energy Arc exiled by Isochron Scepter).
Isochron Scepter and Animate Artifact on the battlefield.
Animate Artifact attached to Isochron Scepter.
You control creatures that can tap to produce at least ({3} magic symbol) .
Steps
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 Energy Arc without paying its mana cost, untapping all creatures.