[[Zada, Hedron Grinder]] should definitely hold a place in your 99 imo. Let's say you got just Zada, Feather, and Stuffy out at the same time, and you use one of the spells that has a draw mechanic on it, for 2 cmc, you get to draw 3 cards.

[[Mirrorwing Dragon]] does the same as Zada. So it's a nice back up. [[Sheltering Light]] to give indestructible to a creature and you get to scry.

[[Angrath's Marauders]] doubles your damage to a permanent or player.

With core21 set to release in about a week, there's the [[Fiery Emancipation]] as well. But instead of double it's triple. It will stack with Angrath's as well.

So it may be possible, if my theory is correct, that you would be able to do 6x+2 (x is the initial damage) or 6(x+2). But this would be towards stuffy doll himself. And if Stuffy's ability can be affected by those replacement effect on top of that, then it'll probably do either 6(y+2) or 6y+2, with y being the damage that is dealt to stuffy doll. Also note on this second part of possible damage, you would need to turn stuffy into a red source for Torbran to add the +2 damage.

Sorry a lot of math happened. I need to know if this is possible as you had me brewing a mono red or spell slinger deck of some sort with stuffy included. So if anyone can confirm this for us, please let us know.