When Fleshbag Marauder enters, each player sacrifices a creature of their choice.
Grixis is a world where the only things found in abundance are death and decay. Corpses, whole or in part, are the standard currency among necromancers and demons.
As Fleshbag Marauder's ability resolves, first the player whose turn it is chooses a creature to sacrifice, then each other player in turn order does the same knowing the choices made before them. Then all those creatures are sacrificed simultaneously.
10-11-2020
wotc
When its ability resolves, you may sacrifice Fleshbag Marauder itself. If you control no other creatures, you'll have to sacrifice Fleshbag Marauder.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.