This is the card that makes Thor's deck powerful, and there are only 3 copies. I think realistically, unless you're playing MP you can maybe luckily send off 2 copies for 16 damage. Either way, turn 1 with Mjolnir you can do 11 damage turn 1. Or 14 if you're packing a Mean Swing. This is the card I mulligan for, not Lightning Strike, or any other card, I want to throw the hammer again and again. Sure other targets like God of Thunder will definitely help, but Hammer Throw will get you to the finish line. Having GoT in play is also key to returning your hammer without having/needing a card in hand, so keep that in mind.
Hero Action (attack): Exhaust Mjolnir → deal 8 damage to an enemy and return Mjolnir to your hand. This attack gains overkill.
"Now, Mjolnir! Strike true" -- Thor
Thor #5. Thor #6-8.