Squire Gone Missing

Whenever a Swamp enters the battlefield under
your control, you may pay {1}{b} to return Bog
Lost Squire from your graveyard to your hand.
Adventurous young men have been to and fro over
Eldraine's lands fair and foul for century after century.
An ignominious death is often met, with no bard to
tell the tale. A mere two words explain their fate a
among the living.