Activate Chromatic Orrery's first ability by tapping it, adding 5.
Cast Mind Games with buyback by paying 4, targeting Chromatic Orrery.
Orvar's first ability triggers, creating a token copy of Chromatic Orrery.
Resolve Mind Games, returning it to your hand.
Repeat.
Once you have infinite mana, you may instead activate the Chromatic Orrery tokens using their second abilities, or target any other permanent.
This brilliant loop revolves around the synergy between Orvar, the All-Form and Mind Games, using the buyback mechanic to keep the spell returning directly to your hand. To fund this continuously, Chromatic Orrery provides the necessary raw power by tapping for five colorless mana while simultaneously allowing you to spend it as though it were mana of any color. Because you will be copying your artifacts over and over, Mirror Gallery ensures that the legend rule won't get in your way, letting you amass an unbounded army of copies and generate infinite mana, cards, and triggers.