Library of the 4th Wall

When Library of the 4th Wall enters the battlefield search your library for {x} non-land
permanents, where {x} is equal to its additional
mana cost. Exile each of them and place them
into the battlefield without paying their mana
cost. If no additional mana was used to cast,
Library of the 4th Wall during this turn, it
instead gains -[when Library of the 4th Wall
enters the battlefield, exile all non-land
permanents, Exile Library of the 4th wall]
—This card is a Land