Everything Everywhere All at Once

This deck use Quicksilver's unmatched ability to ready himself to maximize the usefulness of Maximum Velocity, Moxie, Morale Boost, and Go All Out. In the late game, you can hit 30+ damage in a single turn.

Like many Quicksilver decks, this one is the most vulnerable early on. You need to prioritize getting your key upgrades and supports into place, which can be risky. For a safer setup you can add in the double resources, replacing some of your allies and/or a copy or two of Adrenaline Rush or Civic Duty.

As always, your most important card is Friction Resistance. You can play it directly, or get it with Superpower Training. Similarly, Build Support can get you the Quincarrier. Deft Focus will help you get your other identity specific upgrades into play, and can be used to play Always Be Running if you can't use Friction Resistance.

Your allies are primarily useful for their enter play abilities and to take hits for you. Professor X can also allow you to flip down to alter-ego with less risk.

Going to alter-ego has three main benefits, other than the usual ability to recover and the extra card you get from your increased hand size: You can use Crew Quarters for a bit of extra healing, Serval Industries allows you to put key cards back into your deck (key upgrades early, Always Be Running later in the game), and when you flip back you can play Moxie.

Moxie, Morale Boost, and Maximum Velocity all boost all of your hero-side stats. This gives you a lot of flexibility with your attacks and thwarts. Note that all of these boosts last until the end of the round, not just the phase, meaning your DEF is also stronger. Once you're set up, hitting +3 with these cards is far from impossible, giving you a massive 5/5/5 statline. Specialized Training gives you another +1 to one of your stats, and Adrenaline Rush and Civic Duty can give you another temporary +1 for critical situations.

Finally, Go All Out allows you to exhaust to make an attack that uses the sum of your ATK, THW, and DEF, which can easily hit 15+. In magical Christmas land you may be able to hit two Go All Out on the same turn, but that's not something you can count on.

I've only played this deck solo, but it should work even better in multiplayer if someone can help you survive the first couple of turns. Once you're set up, you can assist as needed. In multiplayer Moxie will also be more useful, as you can play it on someone else on the turns when you're not flipping to hero form.

Removing the flipping element will lower the ceiling of what you can achieve a bit since you won't have access to Moxie and you may find your health running low. Adding in some First Aid can help.