Tir na nOg

Sacrifice this land: Put target Artifact card in
your graveyard on the bottom of your library.
Add {u}. You may only activate this ability if
Tir na nOg is in your graveyard, and only once
per turn.
Whenever this card enters your graveyard, if
there is another card in your graveyard named
Tir na nOg, exile this card instead.