Simulacrum could work as a redirection-type spell. Its Oracle text reads: "You gain life equal to the damage dealt to you this turn. Simulacrum deals damage to target creature you control equal to the damage dealt to you this turn." Good way to channel a bunch of your opponent's damage into one Stuffy Doll.
If you're playing with Crypt Rats, my favorite two cards to pair with them are Touch of Moonglove or Scythe of the Wretched.
- Touch of Moonglove turns it into a boardwipe even when X=1, and then it hits each player's life for 2x their number of creatures.
- Scythe of the Wretched watches Rats kill whatever they kill, including themselves, and then returns them all to the battlefield under your control; if you stack it right, it can even return Crypt Rats last, already re-equipped and ready to go again.
Of course, that's just a cute interaction with a card that wasn't part of your main concept, so feel free to ignore it.
Actually, the more I think about it, I may do this with my Queen Marchesa deck. This allows me to use Wall of Souls as another redirect creature, plus it lets me reanimate my Spitemares and Boros Reckoners after they've taken and redirected a bunch of lethal damage. Using all of these creatures as a rattlesnake to keep the Monarchy generates more card advantage, and it fits the "you did this to yourself" theme.
I've played around with these in a couple decks, but never a deck fully dedicated to it. Looks like you missed Gideon's Sacrifice as a redirection spell (doesn't target, but it takes everything, so a Blasphemous Act could funnel insane amounts of damage to just one of your creatures).
You could run Feather, the Redeemed as the commander. As long as you run enough effects to make your creatures indestructible (stuff like Sheltering Light and Ajani's Presence, which Feather wants anyway) or to bring them back from the dead, Feather would give you extra use out of the targetted damage spells and redirection spells. You could include one or two blink spells to reset who Stuffy Doll is targetting. And Reckless Rage is great in a Feather deck and could be used as both removal and redirected burn in a deck like this.
Finally, there is one particularly funny interaction with your chosen playstyle: Damage Doublers like Dictate of the Twin Gods and Furnace of Rath. Let's say your Stuffy Doll was going to take 5 damage - it gets doubled to 10; however, when it triggers to deal that much (10) to the opponent, it is now doubled to 20. Because it doubles each instance, you effectively quadruple the damage to the opponent. And can you imagine Fiery Emancipation? 5 -> 15 -> 45 !!!