Astral Dragon by paying ({4} magic symbol) ({U} magic symbol) ({U} magic symbol) due to
Doc Aurlock.
When
Astral Dragon enters, it triggers, creating two copies of
Airbender Ascension that are 3/3 Dragon creatures in addition to their other types.
When the
Airbender Ascension tokens enter, they trigger, airbending
Astral Dragon and up to one other creature.
Cast
Astral Dragon from exile by paying ({0} magic symbol) due to
Doc Aurlock.
Repeat from step 2.
Notes
The other
Airbender Ascension trigger can be used to blink creatures you control. You would cast that creature in between step 3 and step 4, blinking it each iteration.