Never bring a spear to a gun fight

Valkyrie struggles to do her thing until she gets Dragonfang down as 2 attack is only enough for the feeblest minions.
Her thing is attacking & killing minions and repeating until there are none left which is why this is a problem.

Aggression is the only aspect to give her multiple ways to boost her attack to give her more consistency and oomph. I have gone for Hand Cannon to keep the overkill train rolling as well as the obvious Combat Training. You could get the same sort of result with Skilled Strike or Mean Swing though the latter relies on getting a weapon too. The red events also help out as they come with a built in ready effect for 1, once you are rolling.

The allies are all great. Thor was not and had to go. Valkyrie is card 42. It's really unclear from the rules whether no subtitle is the same as "Brunnhilde" but there are plenty of Valkyries in the opera that unlike the comics I am familiar with. Card 41 is Death-Glow btw which has poorly formulated rules but I suspect it should be some sort of "permanent" that does not count as part of the deck.

Get Over Here! clears stun or tough and can group minions for "Bring It!" or Thor.

Martial Prowess and Side Holster are a bit marginal as there are not many attack events and Valkyrie's Spear is rubbish and can remain unplayed. This lets you wield guns akimbo and still wave a sword though. The Bifrost has underperformed too (getting more use with more plays).

"Bring It!" is unreliable economy to fit with all the other jank Valkyrie provides. Still it has massive upside and cycling is generally good. Relentless Assault is obvious for a minion muncher. It can be used to ready her her; all her attack events can which is nice. I made 6 attacks in the grand finale turn in my last game - 4 basic and 2 events (plus both Get Over Here!) so suck that Quicksilver!

Sideboard: against big minions in small quantities I have swapped in Skilled Strike for "Bring It!". Against numerous big allies I expect it also be more useful. ("Bring It!" was not so good in this deck as in Thor)