Slum Reaper — ruling 1

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.

Slum Reaper — ruling 2

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

Slum Reaper — ruling 3

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

Slum Reaper : règles, fonctionnement et interactions (MTG)

Slum Reaper is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

When this creature enters, each player sacrifices a creature of their choice.

How it works : Slum Reaper

Original English text — Wizards of the Coast / Scryfall

#1December 7, 2018· Wizards of the Coast
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.
No other card is named in this ruling.
#2December 7, 2018· Wizards of the Coast
If any player controls no creatures, that player simply doesn’t sacrifice anything. Each other player still sacrifices a creature.
No other card is named in this ruling.
#3December 7, 2018· Wizards of the Coast
Slum Reaper may be the creature its controller sacrifices for its own ability.
No other card is named in this ruling.