Yondu's Crimson Bow and Arrow

Try to get Yondu ASAP, then buff his ATK using Energy Spear, Laser Blaster and Inspired to get a very good ally that will have 5 ATK, 0 Consequential damage for attacking and 2 health. Getting the hang of the game while you're waiting for Yondu might be hard, so try not to do reckless discarding, but you can still use Make the Call and Quantum Magic if you accidentally or forcedly end up discarding Yondu. Jarnbjorn is good for dealing extra damage when attacking and can be used with Mean Swing and still get the ability of the weapon. Using Skilled Strike you can get some good basic attacks, but having Heroic Intuition, Combat Training and Armored Vest you can have variety on your turns, and if you feel like you're not gonna use one of those stats you can give them to another Hero.

Overall it depends a lot on luck, but will also require some getting used to a deck based on solely one ally.