Scarlet Witch Mystic Spellslinger

I've only tried this one solo so far. Played and beat all the core box and RotRS villains, losing once to Zola then refined the deck a bit to it's current state.

With Spiritual Meditation you can cycle through your deck pretty quick, I usually spend the first time through getting as many upgrades and supports out as possible while keeping threat in check and getting a few allies to help with threat or minions.

Deft focus makes playing Hex bolt cheaper, using her hero ability as well as Scarlet Witch's Crest makes it a bit more reliable. The Power in All of Us helps for getting out Nick Fury/War Machine/Avengers Mansion/Helicarrier/Quincarrier.

Molecular Decays once the villain is in it's second phase with some Hex Bolts or ally help and they should go down pretty quick once you are set up.