Short version:
Overloader +
Doomsday Assembly +
From the Heavens… yeah, yeah,
Fire Sale and
Partnership Agreement help… but, I think you’re missing the big picture here!
That's it really. Overloader into Doomsday into Heavens. In theory.
It needs a market and it needs more removal to control the board until the combo can go off. It probably wants fewer scrub blockers and more utility to get its combo out.
Fire Sale and Partnership Agreement provide your ramp, but I can't help but imagine an FJT/Creation build of this might get me there quicker. These two cards help my opponents as much if not more than they help me, but this is an explicitly, deliberately janky build I play in casual when I don't particularly want to devote the concentration to ranked, but don't really want to grind gauntlet either.
That said, goldfishing the AI for a few games if you're just trying to kill time can by fun, too.
I seriously can not emphasize enough just how janky something that wants to keep Overloader alive, on a board where Fire Sale and Partnership Agreement are feeding your opponent, long enough to drop back to back 17 to 20 cost effects... But, it's very satisfying and I hope at least entertaining for my opponent when it works!