Preston, the Vanisher | Fiend Hunter | Lumbering Battlement

(and one other card)

Cast
Essence Flux by paying ({U} magic symbol) , blinking
Lumbering Battlement.
When
Lumbering Battlement enters the battlefield, it and
Preston trigger.
Resolve the
Lumbering Battlement trigger, exiling
Fiend Hunter until
Lumbering Battlement leaves the battlefield.
When
Fiend Hunter leaves the battlefield, its second ability triggers, returning any cards exiled with it to the battlefield under their owner's control.
Resolve the
Preston trigger, creating a copy of
Lumbering Battlement that is a 0/1 Illusion.
When the token
Lumbering Battlement enters the battlefield, it triggers, exiling the nontoken
Lumbering Battlement until the token
Lumbering Battlement leaves the battlefield.
The nontoken
Lumbering Battlement leaves the battlefield, returning
Fiend Hunter from exile to the battlefield.
When
Fiend Hunter enters the battlefield, its first ability and
Preston trigger.
Resolve the
Preston trigger, creating a token copy of
Fiend Hunter that is a 0/1 Illusion.
When the token
Fiend Hunter enters the battlefield, it triggers, choose not to exile a creature.
Resolve the
Fiend Hunter trigger, exiling the token
Lumbering Battlement.
The token
Lumbering Battlement leaves the battlefield, returning the nontoken
Lumbering Battlement from exile to the battlefield.
Repeat from step 2.