"Come and Get Slain"

Fear not mortals! The nigh invulnerable Valkyrie is here to clear the battlefield while laughing off the villain's futile attempts to harm her!

On the whole, this deck is pretty simple. Get Tough status cards to avoid taking damage, heal what little damage you do take, lure out minions to feed the Death-Glow, and draw a ton of cards.

Provoking your Foes

Since much of Valkyrie's kit relies on her clearing minions, "Come Get Me, Bub!" is a significant buff to her in Protection, granting both consistency and survivability. Now, the (soon to be) slain can choose themselves.

Hard Knocks is contingent on having enemies to defeat, so with ample targets, it fits well here as both a source of damage and Tough status cards (KTANG!).

By Taunting the villain, we can also convert our spare HP (or better yet, a Tough status card) into more cards in hand. This is a great way to afford Hard Knocks, Have at Thee!, or even just 3 more applications of Death-Glow to mow down a row of minions.

Resilience of a God

You may occasionally find yourself in a slightly awkward position, in which you are already exhausted, and either don't have an attack event, or can't afford it. What Doesn't Kill Me helps alleviate this issue, while providing an additional source of healing. You do need to have sustained some damage to use it, but that's not terribly difficult given the nature of the deck.

Despite virtually never defending, it is shockingly easy to stay at or above 12 HP in this deck. Even when you don't have a tough card to shrug off the blows, between Aragorn and Endurance, you have plenty of room to sustain a little damage, while retaining retaliate from Dauntless. If you ever do dip below your starting hit points, Valhalla, Godlike Stamina, and the aforementioned WDKM can help bring you right back up without ever having to dip down to alter-ego.

Fighting Alongside Friends

This deck is intended for use in multiplayer.
As with many Valkyrie builds, this deck can struggle with thwarting. It also doesn't lend itself to rushing the villain, rather preferring to whittle away their health and outlast them. This can be difficult in solo, but it shines in 2 player where there is a less need to manage everything.
It's for this reason, primarily, that we justify the use of Muster Courage; share Tough cards with your friends so that they don't mind handing your share of the thwarting. (This is also under the assumption that you are playing Expert; 4ER for a single tough is not worth it, so in Standard, or if facing a villain without a stage number, you'll want to swap this for something else.)

Abundant Wealth

Chooser of the Slain, Taunt and Valhalla ensure that you will have plenty of resources, even for the pricier 3-cost cards. It also helps us dig for important cards early in the game. Do not be afraid to take some undefended attacks if it helps you get set up faster.

You may also notice that there are a lot more resources than anything else. This is great for What Doesn't Kill Me, and much less great for Seduced or Trouble in Otherworld. Fortunately, you'll only have to deal with the later once and it's removed from the game, and you only have to deal with the former if you draw Shadow of the Past. My advice is to just not draw Shadow of the Past.

If you're deeply concerned about it, a more conservative version of this deck might drop Dauntless and 1 copy of Taunt (or Muster Courage in solo) to make room for a couple copies of Get Behind Me!. Although taking an attack is not usually a worth while trade-off for treachery cancellation, we have a large enough health pool and we take sparse enough damage that it might be worth it just to avoid a game ending Enchantress.