Arni Metalbrow | Thousand-Faced Shadow | Cloudstone Curio

(and one other card)

Declare
Priest of Urabrask as an attacker.
Arni Metalbrow triggers, causing you to pay ({1} magic symbol) ({R} magic symbol) to put
Thousand-Faced Shadow from your hand onto the battlefield tapped and attacking.
When
Thousand-Faced Shadow enters the battlefield, it,
Arni Metalbrow and
Cloudstone Curio trigger.
Resolve the
Cloudstone Curio trigger, choosing to return nothing to your hand from the battlefield.
Resolve the
Arni Metalbrow trigger, choosing not to pay.
Resolve the
Thousand-Faced Shadow trigger, creating a token copy of
Priest of Urabrask that enters the battlefield tapped and attacking.
When the
Priest of Urabrask token enters the battlefield, it,
Arni Metalbrow and
Cloudstone Curio trigger.
Resolve the
Priest of Urabrask trigger, adding ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) .
Resolve the
Cloudstone Curio trigger, returning
Thousand-Faced Shadow to your hand from the battlefield.
Resolve the
Arni Metalbrow trigger, causing you to pay ({1} magic symbol) ({R} magic symbol) to put
Thousand-Faced Shadow from your hand onto the battlefield tapped and attacking.
Repeat from step 3.