Slum Reaper

Official Ruling

If any player controls no creatures, that player simply doesn’t sacrifice anything. Each other player still sacrifices a creature.

Official Ruling

As Slum Reaper’s ability resolves, first the player whose turn it is chooses a creature they control, then each other player in turn order does the same, knowing the choices made before them. Then all the chosen creatures are sacrificed at the same time.

Official Ruling

Slum Reaper may be the creature its controller sacrifices for its own ability.