Infinite creature LTBInfinite creature ETBInfinite creature sacrifice triggersInfinite death triggersInfinite colorless manaInfinite creature tokensInfinite creature token copies of all noncreature permanentsInfinite recursion of creature cards in your graveyard
How it works
Cast Everquill Phoenix for its mutate cost by paying 3, mutating it over or under a non-Human creature you control.
Everquill Phoenix triggers, creating a Feather artifact token.
Cast Astral Dragon by paying 6.
When Astral Dragon enters the battlefield, it triggers, creating two copies of the Feather token that are 3/3 Dragon creatures.
Activate Ashnod's Altar by sacrificing Astral Dragon, adding CC.
Activate a Feather by paying 1 and sacrificing it, returning Astral Dragon from your graveyard to the battlefield.