One of the things I love most about Stuffy Doll is that it can go into any color deck, and make it work well. So I’ll be going through some options in WUBRG order, mentioning some multicolor highlights along the way.

White

One of the best options in White is possibly Guilty Conscience. Whenever it deals damage, it is dealt that much damage... so it deals that much damage and is dealt that much damage. Though this may seem like an infinite loop, it will stop once the chosen player is dead, as Stuffy Doll can no longer deal damage to them because they are removed from the game by dying.

White also has a lot of ways to gain Lifelink (or similar effects, like Spirit Link), which on a Stuffy Doll can still get you two life a turn, assuming you aren’t given a chance to block with it.

Speaking of a chance to block, some opponents may use a go-wide strategy, thinking your creature can only get in the way of one. Don’t let that stop you! There are a few instants that let a creature block any number of creatures, and Entangler is an enchantment that lets you block everything (without evasion) each turn. They attack with 40 Saprolings? Good! You’re about to deal 40 damage to the chosen player.

And when evasion doesn’t allow you to block, Pariah can reroute any damage to you to your Stuffy Doll instead. Channel Harm does a similar effect, but at instant speed.

Red is perhaps the best complement to white for Stuffy Doll, allowing direct damage and a great symbiosis of lifegain and direct damage.

Blue

Blue’s main trick is to protect the Doll. One -1/-1 counter and the doll has 0 toughness and goes to the graveyard. Bounce can also be used to choose a new player when you’ve taken care of the first, counterspells can protect it from Pacifism and similar effects. If you want to complicate combat for your opponents, there are a few Jellyfish (Gomazoa, Guard Gomazoa) or Fog Bank-type effects to dissuade opponents from sending attacks your way.

 Blue also has Clone effects, such as Followed Footsteps, which also allow you to create other Stuffy Dolls, so when you are attacked you choose which player will actually be taking the damage.

Since Blue is the most reactionary color, make sure not to tap Stuffy Doll until the end of the turn of the player before you. Not only will the Doll be available to block, but you can have something like Ophidian Eye to give it additional purpose.

Honestly, Blue mostly uses the Stuffy Doll just as support, rather than as a win condition. You can make it a more central part of the deck by adding Green for +1/+1 counter theme, but we’ll get to that later.

Black

Stuff Doll is indestructible, so though it won’t be killing creatures on its own, it may last longer than most creatures. Damnation can clear a board that’s getting too big for Stuffy doll, along with other, similar effects.

With these other creatures dying, feel free to give Stuffy Doll a more active role than just getting survivor’s guilt. Eternal Thirst gives it a +1/+1 counter whenever a creature controlled by your opponent dies, and with the path cleared, Stuffy Doll can become a beater.

If you’re playing a multiplayer game, Assault Suit allows your Doll to go around the table and either attack or use its tap ability to deal with the chosen player. Sadly, this does remove it as a blocker for you, but does pump it up a bit. Why do I bother bringing that up in the Black section? Ragged Veins has Flash, so if someone does attack or use the ability of your Doll, they are the controller, and they feel the pain inflicted upon it. Binding Agony does the same thing, but not with Flash, means one damage from the Stuffy Doll is 2 damage to its controller, and it normally deals one to itself and one to an opponent, so 2 to chosen player and 4 to controller.

Black mixes well with Red for direct damage and keeping the threats limited to hits your Doll can take.

Red

Red loves Stuffy Doll.

You tap your Doll to deal one damage to it, but Dictate of the Twin Gods says “No, that should be two!” Furnace of Rath overhears and says, “FOUR!” Angrath’s Marauders doubles it again to eight. And then the Stuffy Doll tries to deal that 8 damage, but it’s again octupled to 64. And yes, having all 3 out would be rare, but is possible. But even a single one of these makes the tap ability of Stuffy Doll deal 4 damage to a player instead. Blocking with the Stuffy Doll can quickly turn deadly.

Direct damage, even not doubled, can be fatal quickly. Star of Extinction or Blasphemous Act are great ways to deal large amounts of damage across the board. (Tamanoa and Soulfire Grand Master are great reasons to add a few more colors if taking this approach. Just Stuffy, Soulfire, and Tamanoa out when you cast the Star would net you 120 life, and that’s ignoring anything your opponent has).

Red goes well with white for lifelink, or with green to make your doll a creature that needs to be blocked.

Green

Green is fun for changing how you use Stuff Doll. You can still use it the traditional way, dealing damage out one at a time, but why would you when you can make a Stuffy Doll into a stuffy dreadnaut? Rite of Passage can make Stuffy Doll start making trades when blocking, before you start attacking in. Putting a Lure on a Stuffy Doll means all the possible blockers will be intercepting it, racking up the damage quickly.

If you are collecting +1/+1 counters, make sure to include a Crowned Ceratok, so even being chump-blocked doesn’t stop the damage from going through.

Also, if you’re playing green and want some creature tokens in case your opponent goes wide, perhaps add a Druid’s Call to make sure when your Doll taps (for its ability or attacking) you’re getting a squirrel to replace it as a blocker.

Green likes white for adding vigilance when it’s attacking, so it can still block, or red to pump it or hit it, or even blue to use things like Vorel to make it the growing threat on the board. 

If you want to multi-color, putting it with other creatures with similar abilities brings you into Naya (red, white, green). Enrage is bringing out a lot of options with Ixalan, so be sure to pick some up. Gishath doesn’t go well with the Doll, as it will pass right over it when triggered, so perhaps check out Marath or Samut instead.

If doing a two-color deck, green/blue is good for pumping up a Stuffy Doll. If in Commander, I suggest Ezuri, Claw of Progress. Use blue cards to find the Doll right away, and green to ramp and cast the doll sooner.

For red/white, you have a lot of options, but stay away from Gisela, Blade of Goldknight. If your Stuffy Doll would be receiving one damage, it actually takes no damage, due to the prevention rounding up. This is avoidable with anything that deals more than one damage, or if doubling damage by other means, but is a significant interference in using a Stuffy Doll. Avoid Iroas for much the same reason, though limited to combat, but any amount of damage. Razia or Aurelia are probably best, one allowing you to redirect damage to the Doll, and the other allowing your Doll multiple combats to trigger.