Mechtitan Core | Astral Dragon | Encroaching Mycosynth

(and two other cards)

Cast
Astral Dragon by paying ({6} magic symbol) ({U} magic symbol) ({U} magic symbol) .
When
Astral Dragon enters the battlefield, it triggers, creating six token copies of
Mechtitan Core that are 3/3 Dragons in addition to their other types.
Activate
Krark-Clan Ironworks twice by sacrificing two of the
Mechtitan Core tokens, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) .
Activate a
Mechtitan Core by paying ({5} magic symbol) and exiling it, three other
Mechtitan Core tokens, and
Astral Dragon, creating three 10/10 Mechtitan legendary creature tokens.
Put all but one of the Mechtitan tokens in your graveyard due to the legend rule.
Mechtitan Core triggers twice, returning all cards exiled to create the Mechtitan tokens from exile to the battlefield.
When
Astral Dragon enters the battlefield, it triggers.
Holding priority, activate
Krark-Clan Ironworks by sacrificing Mechtitan, adding ({C} magic symbol) ({C} magic symbol) .
Resolve the
Astral Dragon trigger, creating six token copies of
Mechtitan Core that are 3/3 Dragons in addition to their other types.
Repeat from step 3.
Once you have infinite ({C} magic symbol) , you may forego sacrificing
Mechtitan Core tokens to
Krark-Clan Ironworks, and then target any other applicable permanents using
Astral Dragon.