Null Ring

When Null Ring enters the battlefield, choose an
artifact's name, with mana cost {1}. Destroy all
cards sharing the chosen name.
Whenever an artifact sharing the chosen name
enters the battlefield, destroy it.
{t}: Activate only in response to a triggered ability . Exile an artifact from target opponent's graveyard sharing the chosen name. The ability triggers an additional time.
The third time Null Ring is tapped, exile it.