God of Thunder, the Man, the Legend!

First rounds buy Combat Training as soon as posible to have Att 3 and the freedom of using Mjolnir as resource early on. If ot possible equip Mjolnir.

God of Thunder are top priority upgrade (even before Asgard), pays for itself quickly and enables good Lightning Strikes, Hall of Heroes is also top priority.

Defender of the Nine Realms is a key card, worth saving in hand. Excellent twart value + generates minions for Hall of Heroes. Don't be afraid of accumulate minions but only with Hercules and/or big Lighting Strike on hand.

Main strategy is stay in Hero Mode as longer as possible. Don't let your 4 card hand fool yourself - it's powerful enough plus Minions during Villain phase gives you 2 cards, and then Defender of the Nine Realms can generate more. Don't defend if possible because Thor's attack is needed most of the time. Flip to Odinson to Recover, call Mjolnir after Hammer throw round or prepare a big round with Hall of Heroes.

Mid game, play your allies, and use them to Thwart, last hit minions or defend (specially with Hulk - insane HP value, don't attack with him unless is greatly needed). Late game Invulnerability can save your allies to great following round. Remember that Get over here can activate Jarnbjorn for cheap 3 dmg (1+2).

Late game you should be a beast who can deal 20 dmg easily, and if you start the round as Odinson with Hall of Heroes enabled and a Defender of the Nine Realms you have an extremely powerful round of 11-12 cards.