How exactly does Fleshbag Marauder work?
From the card, it seems pretty obvious… you need more than one creature in play, and if you do, you sacrifice your first creature to kill your opponent’s first creature.
If you have another creature when Fleshbag Marauder comes into play, you are given an option box to select a creature, which seems superfluous, since as the card describes it, there are no options to take. You can also choose not to sacrifice a creature.
Yesterday I tried to select a different creature, other than first creature, to see what happened; no sacrifice/destroy effect occured. Unfortunately I don’t remember the exact state of the board, I merely assumed that I tried to create an effect that was not allowed by the card and so nothing happened.
Today, however, I was in this situation: My opponent had a Blight Herder, and I had a Fleshbag Marauder (in position 1) and an Erebos’s Titan (in position 2). I cast another Fleshbag Marauder, selected the Erebos’s Titan, and both the Titan and the Blight Herder were destroyed.