Thor

The general idea is to play out your upgrades and supports as soon as you can so you can spend your turns playing allies with The Bifrost and dealing damage with Hammer Throw, Lightning Strike, and your basic attacks.

Thor's innate hand size is really bad. You're meant to offset it with "Have at thee!" triggers and Asgard. To that end, mulligan for Asgard or For Asgard! to find Asgard. Don't worry about "losing" cards that you discard, Thor draws enough cards that you're going to be going through your deck pretty quickly. This deck can offset the lower hand size without Asgard, but it's just much more consistent with it (especially early on).

Between Target Spotter guaranteeing "Have at thee!" triggers during the villain phase and Defender of the Nine Realms, Spoiling for a Fight, and Angela triggering "Have at thee!" during the hero phase, you're going to be drawing 4 extra cards most turns. This means you're generally going to be limited by resources instead of cards, so get those generators out!

Godlike Stamina and your 22 health should give you quite a lot of leeway in terms of when you kill the minions you're engaged with. You don't get any rewards for actually killing the minions, so there is value to keeping 1 or 2 low attack minions around for slightly larger "Bring It!"s while you look for Lightning Strike.

The Bifrost and the allies you can play using it are your main form of defense. You will generally be able to get quite a lot of damage out of your allies before defending, so get them into play even if you don't immediately need the defense. Between all the readies, you will generally be able to recover whenever you flip to alter-ego, so take advantage of the 4 recovery and tank some attacks to squeeze a couple more activations out of your allies if you can.