You can either run that creature into blockers, or sacrifice it to one of your own abilities for a benefit
To resolve Sheoldred's enters-the-battlefield ability in a multiplayer game, the next opponent in turn order (or, if it's an opponent's turn, the opponent whose turn it is) chooses a creature they control to sacrifice
Partner (You can have two commanders if both have partner.) The damage the commander deals as a result of Kediss's triggered ability isn't combat damage
Regardless, if we're getting anyone, I'm glad it's Larry
The effect itself is quite powerful, and with Trap Trickhe can bring Welcome Labrynth and so on to easily fulfill the conditions
negate that face-up monster's effects until the end of this turn, then, if you control a Link-2 or higher "Marincess" monster, all face-up monsters you currently control are unaffected by your opponent's card effects until the end of this turn