I originally built this deck as a joke just for the eye candy, but it works surprisingly well.
Card descriptions:
Thena, Angela, and Kitty Pryde
A very reliable trio in the current meta. Playing Thena on turn 2 and then constantly powering her up by playing Kitty Pryde and other card every turn allows you to get power into at least two of the three lanes each turn. It may not be huge power, but it will grow to a considerable amount throughout the match. Considering that this deck has a low Cost curve, it’s very likely that you will be able to play two cards during most turns.
Elektra
There are many 1-Cost cards that provide considerable power/benefit over the course of a match, such as Ant-Man, Nebula, or Sunspot (or Quinjet in the case of an Arishem deck). Elektra allows you to snipe one of them during turn 5 or 6 at a very cheap cost while still allowing you to play a beneficial card such as Captain Marvel in later turns. Even though a card such as Shadow King would theoretically do Elektra’s job better by also resetting the power of non-1-Cost cards, a Elektra + Valkyrie play on turn 6 can win you a filled lane regardless of power if your opponent has any 1-Cost card there. With Valkyrie, power doesn't matter as much as you having more cards in a lane than your opponent to guarantee a win.
Snowguard
What looks like an outsider in this deck, Snowguard gives you two additional 3-Cost cards to make sure that you can continue powering up Thena on Turn 4 or 5, but the Hawk and Bear auroras give a surprising amount of benefit and counterplay. Use Snowguard Bear to win Savage Land or Shadowland by locking your opponent out of that lane early. Snowguard Hawk is great for getting into hard-to-reach locations such as Sanctum Sanctorum (if you don't pull Captain Marvel) or stopping the effects of negative locations such as Thunderbolts Tower. Hawk is also one of your ways to sneak an early win out of your opponent, especially if they’re playing a combo deck that relies on a huge turn 7 play, by playing Magik early and then using Hawk and another card on turn 6.
Dazzler
Even though Dazzler may not become as big as she could be in an Ultron or zoo deck, she is an important piece to allow you to win a filled lane. If your opponent has filled their side of a lane and you have Dazzler and two other cards on your side, you will always win by 2 by playing Valkyrie in the last spot on turn 6 (unless one of the enemy cards has an Ongoing effect that determines its power, such as Darkhawk).
Magik
You can use Magik either offensively or defensively depending on the situation. If you want to extend the game to continue powering up your Thena or need to fill more locations to power up your Dazzler, Magik gives you some extra time. You can also use Magik and then play Snowguard Hawk on turn 6 as previously mentioned to end the game early, potentially catching your opponent off-guard.
Enchantress
Possibly the only card that doesn’t synergize directly with the rest of the deck, Enchantress isn’t a 4-Cost powerhouse or anything. However, she is invaluable when playing against Tribunal, Negative, or Spectrum decks and should allow for an immediate snap if you see your opponent setting up an Iron Man + Tribunal combo, for example. Enchantress can also cancel out your opponent's Luke Cage to prevent your endgame Valkyrie play from being stopped.
White Queen
A decently powered 4-Cost card which also gives you information about what your opponent’s turn 6 play might look like so that you can prepare for it. Copying your opponent’s Galactus will tell you to make sure that you have power on empty lanes while pulling a Knull could win you a lane by itself by playing it on the last turn after your opponent does their big turn 5 or 6 destroy combo. Copycat could also work here if you have her.
Captain Marvel
A very versatile card and one that is very useful in games which contain hard-to-reach locations such as Death's Domain. She’ll win against Jeff if your opponent is banking on that card to win a location. If you plan correctly, you can also power up Dazzler by allowing Captain Marvel to move and fill up a lane on the last turn. She is also a failsafe in case you don’t calculate your last-turn Valkyrie play correctly (your opponent plays 2 cards instead of 1 in a certain lane and you’re therefore losing by 3 power, for example) as she’ll move to win it for you.
Valkyrie
One of the most important cards in the deck and one that combos with most of the cheaper cards to allow you to win otherwise losing lanes. Excluding Ongoing cards that base their power on hand size or the board state, you can always win a lane if you match the number of cards that your opponent has on their side of the field while including a card that can be powered up on your side such as Angela, Thena, or Dazzler. If an opponent has 4 cards including any 1-Cost card on their side of a lane and you have 2 cards there, you can win 12-9 by playing Valkyrie and Elektra there on turn 6 without the help of Thena or Angela. If your opponent has a powerful Ongoing card such as Ajax that Valkyrie won’t affect, you have Enchantress to counter it.
She-Hulk
She-Hulk is your biggest “power play” in this deck but she is able to be played early most of the time. As you’ll most likely be trying to play two cards each turn to power up your Thena, you could play Kitty Pryde and another 1-Cost card on turn 4 and then play She-Hulk and Kitty Pryde (or another 1-Cost card) on turn 5. As Thena will continue to be powering up, this results in a surprising amount of power spread across multiple lanes. She also combos well with Magik as she can be played for free if you skip turn 6 and plan for a big turn 7 play.