The Arkstone

Treasure affinity — Costs {1} less to cast per each trasure token you control.

Equip legendary creature {1}. It can´t be unequipped. At your end step, equipped creature gets a Madness counter. If it has five or more, exile
it. If it is equipped, spells or abilities using or
creating treasure tokens trigger an additional time.

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