Construct of the Hollow

When this Construct is cast, exile all artifacts
on the battlefield. For each artifact exiled by this
Construct, you may play an artifact from any
graveyard without paying its mana cost.
During your end step, this Construct's controller
must pay {u/b}{u/b}. If they do not, return all
cards exiled by this Construct to the battlefield
and exile this Construct.