Decklist!
OP:
This is an incredibly stupid idea...maybe more like an achievement to unlock, but it makes me laugh so I kinda want to try to do it.
The commander that made me think about it is Kardur, Doomscourge. His wording is the same as goad has always been, but for some reason while reading it this time an idea struck me - the duration of his etb trigger is "until your next turn"...well, what if you NEVER TAKE ANOTHER TURN! CHECKMATE!
My next thought was "well, that's a very silly way to come in second". Your opponents are forced to attack each other, but ultimately it'll be 1v1 and you have no more turns. So...that's not going to end well.
Or is it?
Kardur's got another ability, which conveniently drains the life from your opponents while they're forced to beat the crap out of each other. But unless you get spectacularly lucky, that's probably not going to win you the game. But it definitely helps. What you need is just a little bit of *extra* help. Stuff like Revenge of Ravens and Hissing Miasma...maybe some Sulfuric Vortex, Roiling Vortex...and of course, make sure they've got plenty of tokens with Akroan Horse, Genesis Chamber, etc, lots of little small bodies to help ensure that combat is frequent, and results in lots and lots of death.
There aren't a ton of cards that last "until your next turn", but any negative "every upkeep" effect does work, plus anything that triggers on things your opponents are doing but you won't be, like Pyrostatic Pillar and Spellshock. Finally, if you want to get lazy with your Saw-esque house of horrors you're creating for your opponents, you could always sandbag one last burn spell to try to finish off the last opponent and catch them unaware, but frankly I think it's a lot funnier if you can create a board state so hostile that they can't figure a way out alive, even without your interference. What could be more rakdos than that?
Anyway, as far as "stuff to look for", so far I've got:
Lethal Vapors (plus a ton of tutors for it obviously since it's the crucial piece of the puzzle)
"until your next turn" effects, primarily Kardur.
bad "every upkeep" effects.
bad "whenever you do X" effects, where X is something people are probably going to do like casting spells, drawing cards, attacking, etc.
effects that grant opponents tokens.
possibly one efficient last-ditch burn spell
Any other ideas to contribute to this stupid nonsense are greatly appreciated.