Psychic Puppetry in exile (exiled by Isochron Scepter).
Isochron Scepter and Zirda on the battlefield.
({2} magic symbol) ({R} magic symbol) available.
Steps
Activate Isochron Scepter for ({1} magic symbol) .
Splice Desperate Ritual onto Psychic Puppetry for ({1} magic symbol) ({R} magic symbol) , and have Psychic Puppetry target Isochron Scepter.
Resolve the spell, untapping Isochron Scepter and adding ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) .
Repeat as necessary, using ({R} magic symbol) to pay for the Isochron Scepter activation and ({R} magic symbol) ({R} magic symbol) for Desperate Ritual.