Rolan, pitiless Mayor

Whenever one or more opponents create or sacrifices a trash token, you get a map piece.
At the begining of your first main phase, if you have 4 map pieces or more, you may return a creature or artifact from a graveyard onto the battlefield under your control untapped. You then lose life equal to the number of creatures you control but dont own or the amount of time you used this ability, wichever is greater.