Eye of Sauron

Hexproof, indestructible. Cannot be exiled from
the battlefield. When this becomes attached to
"The One Ring," you may search your library for
"Sauron, The Deceiver" and put it onto the
battlefield tapped, then exile this and attach
The One Ring to it. When a black creature enters
the battlefield, gain control of it.
{t}: Target opponent reveals a card of
their choice from their hand.