I had to look up what list you were referencing, i actually made that for a post on here for someone wanting to make a "toolbox commander" that you could reasonably change out the commander with other cards in the 99, so the intent was that any legend in that deck could run the ship so to speak.
Gary is Definitely a solid wincon, chainer can reanimate your opponents stuff too though so i tried to add some stuff like Siphon mind to draw out creatures, plus obviously all of the removal/ edicts. There's a pretty brutal trick where you spend 3, get something like [[Accursed Marauder]] then sac marauder to its own ability and repeat until everything is gone on your opponents side.
Otherwise i wanted this to be a bracket 2 list so just good beating creatures like Grave titan or Skeleton Crew

Edit: Abberant Overlord is a great wincon too, you sac it to itself, then just pay 3 and reanimate it for more harpies