The One Ring

Indestructible, hexproof. Bounty Artifact (Whoever defeats you or kills equipped creature, gains control
of this artifact.)

{1}: Equipped creature phases out or gains double
strike, and gains Ring Counters equal to its power.
Roll 1D20 and if is less than its Ring Counters exile
the creature and create a 2/2 Ring Wraith token.

Equip legendary creature {1}. The One Ring can´t
be unequipped.