Some cards embody the essence of an archetype so well that you have to stop and appreciate them. Doppelgang is the pure distillation of over-the-top Simic nonsense to the point where you don't need to have any other cards in the entire deck that support Simic nonsense, and you'll still do a lot of Simic nonsense with this thing. This article is going to deviate a bit from my usual single-deck format because I built this card a couple of different ways and still feel like there is plenty of untapped potential.
What does this card want?
Doppelgang wants to clone things, but its least expensive mode is only a single permanent copied for five mana. While this isn't objectively terrible when compared to older cards like Clone or Clever Impersonator, it leaves something to be desired by today's standards. Once you can get X to equal two, however, things start to get interesting. For seven mana, we can create a total of four clones, two of each of two targets, and it scales from there.
In order for this effect to be worthwhile, we need to make sure there are permanents on board to copy and that we have ways to cast this outrageously expensive spell. Our opponents will likely help by having some permanents of their own, but let’s explore some things we can bring to the party to elevate this thing.
How are we casting it with a high X?
There are three methods to consider for getting Doppelgang to do the thing: ramp, cost reduction, and/or control. Ramp and cost reduction both work by getting you ahead of the curve so you can cast large spells prior to your opponent, where control needs to be coupled with card draw and a high density of lands because it relies on playing a land each turn and simply surviving long enough to cast the huge X. Decks should incorporate a blend of these, and the nice thing about Doppelgang is that it helps fuel future casts by copying lands or permanents that help with ramp/cost reduction.
Ramp
Ramp (named after the card Rampant Growth, by the way) is a classic strategy. In this case, I like to rely on permanents that help us ramp like Topiary Stomper and Spelunking because they give us material on board that Doppelgang can copy. Note that, if you're going for Topiary Stomper or Invasion of Zendikar, make sure your deck is packed to the gills with basic lands.
Other alternatives are treasure generators like Stimulus Package or Charming Scoundrel. I especially like Charming Scoundrel because it offers card draw or even a win-con if Doppelgang goes off.
Cost Reduction
Cost reduction is a little slower and less universally useful than ramp, but the synergy with Doppelgang and Hinata, Dawn-Crowned is pretty spectacular. Given that cost is reduced for each target, and Doppelgang's X sets the target, it effectively knocks an X off the cost. If we can get multiple Hinatas online (thank you, Mirror Box), we can reduce the cost to as little as GU and get as many copies as there are permanents on the field. On MTGA, this has been known to crash the server. This will result in going mana positive and possibly drawing our whole deck, so be careful.
Control
This option is pretty straightforward. Cards with flash or non-creature spells work very well in these shells because you'll probably want to run a few creature-focused board wipes. Classics like Wedding Announcement or The Restoration of Eiganjo can tie the room together nicely and make sure you hit all your land drops with a well-timed Sunfall or No Witnesses to keep you alive. Also, No More Lies has performed well for me in the decks where I've run it. The difference between having to pay two versus three is massive.
This strategy also lines up nicely with Mindsplice Apparatus and other flash permanents.
What are we copying?
For every type of effect, there's a permanent somewhere that provides it. We have removal with Leyline Binding or Ossification, we have card draw with Spirited Companion or Inspiring Overseer, and we even have tutors and reanimation with Cruelty of Gix. That said, one card took the cake in every build I tried.
The synergies between Three Blind Mice and Doppelgang are mind-blowing. Three Blind Mice allows you to copy any token on chapters two and three. This can be used alongside Tamiyo, Completed Sage to create a loop where the saga copies the token saga that can copy the token saga and, before you know it, you have inevitability your opponent has to race unless they're running mass enchantment removal like Fade from History or Farewell.
Given that Doppelgang creates tokens that are copies of anything you want, it can copy the saga and start the chain even without Tamiyo. Additionally, Three Blind Mice can make token copies of other tokens Doppelgang was able to create, assuming the first Doppelgang resolution didn't result in your opponent scooping.
Winning Versus Win More
“Win more” is an expression often used to describe powerful effects that help close a game out but are often only useful when applied to an already winning board state (think Unnatural Growth). Doppelgang will probably go down in history as a “win more” card in most people's estimations, but I honestly believe there are situations where it's uniquely poised to generate value that can turn a losing position into a winning one if you are creative in its application. This can be accomplished by using it to clone your opponent's permanents situationally. Clone effects have always had this opportunity and Doppelgang being able to target any permanent gives it a unique advantage. Copying your opponent's Liliana of the Veil or The Wandering Emperor to kill a lethal threat or copying an Atraxa, Grand Unifier or Sheoldred, the Apocalypse can stabilize a board when you otherwise wouldn't have a chance.
Don't be afraid to leverage an X=1 cast of Doppelgang to pull you out of a tough spot. Run four copies and maybe ways to recur it (like Shigeki, Jukai Visionary) and you'll see what I mean.
The Bottom Line
Creativity is key in both deck building and playing cards like Doppelgang that rely so heavily on board presence. I've experimented with this card in a number of builds, and I barely feel like I've scratched the surface. While it looks like an outlandish Commander-only card, I honestly think it has potential in formats like Standard. Although, I'm realizing it was rude of WotC to put green in its casting cost so you can't run it in a Hinata commander deck.
Oh well. That’s probably for the best.