Quicksilver - Always Be Stunning

This is Quicksilver Stun-Lock, straight up. Keep the villain stunned as much as possible while you build your board. It plays slowly but very reliably. On your first pass through your deck, Friction Resistance is your most important card, but you should basically just try to hold the line and build your board until you've gone through your deck at least once and have a bunch of Upgrades and Supports out (with Avengers Mansion and Reinforced Sinew always being good). Once you feel sufficiently built with stat upgrades and resource generators, then switch to some beat-down turns where you stack a few copies of Always Be Running onto a Maximum Velocity.

The other defensive stuff and two copies of Med Team are mostly just to keep Quicksilver alive while he gets set up - 9 hit points don't go far. The Night Nurse does double duty for both light healing and stun removal, as she always does.

I'm on the fence about adding a third Tackle. It's good but it's always an expensive card to play and this deck usually manages enough stun without it (however, some of that depends on how reliable you are in getting Never Back Down to stun. For villains with few minions and more big swings, I would probably trade out one Never Back Down for a third Tackle.

Finally, don't be afraid to feed your cheap allies to the villain as blockers when you haven't managed to stun, especially if you aren't confident that you can stun with a Never Back Down. It's better to toss Ironheart or Clea to the villain while Quicksilver blocks a minion and triggers Unflappable. Both of them, along with Mockingbird, are basically just speedbumps for the villain while you get built up.