This deck is based on the fact that Kraven triggers on movement on BOTH sides, including your opponent, so the idea is to use some jukes early game to keep your opponent guessing, and then shake up their strat with some movement control later via Polaris, Aero, and Magneto.
Otherwise it's kind of your basic Movement deck, but I like it a bit better than the standard shell because it gives you some more flexibility. Instead of always moving your own stuff, you have some disruption cards that can mess up your opponent's board while also helping you win by buffing your Kraven, or allowing you to win lanes you were previously losing. Having said that, let's talk about some card choices, and some possible replacements for them.
First, the irreplaceable cards:
Kraven - Yes, you need Kraven in a movement deck. In particular, you can't have this specific deck without him because the whole thing is built around him triggering on both sides.
Vulture - in any movement shell, I think Vulture is absolutely essential. He gets an absolutely insane +5 power just for moving one time, and because of it can get out of control really fast.
Add to this that both of these cards are in a movement deck in the first place, which makes it almost impossible to counter them with things like Shang Chi.
Movement is slippery, and that's why I like the archetype so much. Any archetype can put a lot of power on the board and protect it, but few can simply avoid threats rather than counter them outright.
Now, let's move on to the pool 3 cards that some of you may be looking for replacements for.
Human Torch - Johnny is a fun card, but with Killmonger being so prevalent, he's not the most solid choice esepcially since he really wants to be played early. That being said, he's usually at least 4 power if you play him turn 4 or 5, which may allow you to bait a Killmonger by playing Iron Fist and Nightcrawler. He is a pool 3 card, though, so if you'd like to replace him, I recommend either a utility 1-2 drop like Iceman or Scorpion or something, or Dagger who has a similar effect. I actually haven't tested Dagger in this setup, but since she works based on the opponent's cards, she might actually be better than Johnny here, since you can play Aero or Polaris, then move Dagger to that spot for a nice buff. She's also immune to Killmonger which is really nice.
Polaris, Aero, and Magneto - I would hope that, if you're interested in this deck, you have at least one or more of these cards. The most replaceable of them, in my opinion, is Magneto. Being a 6 cost card, you will often have to choose between him and Heimdall, and each have their own situational advantages and disadvantages. The second most replaceable is Polaris. Is she good? Yes, quite good actually. Kraven into Polaris in the same lane is usually pretty strong, netting you 9 power in 1 lane, and that's before other stuff moves into Kraven's lane. I think Aero is almost required, though. Her effect is VERY difficult to replace because it's controlled, IE you know where the cards your opponent plays are going. You could replace any one of these cards with Juggernaut, though, as although his movement is random, he functions very similarly to all of them but most notably can replace Aero pretty effectively as long as you can think in terms of "I don't want things in this lane" instead of "I want things in this lane instead of others". Unfortunately, there aren't really any great Pool 1-2 replacements for them though. One last thing you could add here instead of one of these cards, though, is Kingpin. You have to be careful with him as he can destroy your stuff too but, much like Kraven, he affects both sides and tends to work really well with things like Aero and Magneto, or even Juggernaut if you're feeling lucky. There's also a lot of potential for mind games with him using a turn 5 Cloak because then your opponent is in a tricky spot: Are you going to move Kingpin and play Magneto/Aero in Cloak's lane, or are you just going to play them in Kingpin's lane?
And now that we've gone over the pool 3 cards, let's talk about some of the strategies here with certain cards.
Storm - I really like Storm as a control card; she creates very interesting situations and opportunities for mindgames. Flooding a location gives you the ability to counter locations that may perturb you, like Fisk Tower, or that help your opponent more than you, like Onslaught's Citadel, and since your opponent probably isn't playing a Movement deck, she ends up shutting down a location for them where you can simply move stuff into the flooded area. With Magneto and Polaris in the deck, you can also play Storm, and move stuff they play before the location is flooded (or in Aero's case, while it's flooding), thus allowing you to win the lane even if Storm is the only card there (assuming no Dr. Doom, Ultron, or Squirrel Girl shenanigans). She is really versatile, but she's quite replaceable too. I think you could easily replace her with Cosmo for example. Sure, he messes with your play too, which is why I prefer Storm, but he also gives you an answer to Wong and a lot of other stuff that can vex you.
Cloak - Much like Kraven himself, it's easy to forget that Cloak allows your opponent to move cards to his lane too. This is an advantage, though, because if they do, and you also have Kraven there, that's 2 power for each one they move. I also really like playing Iron Fist > Cloak on occasion so you can get an empty lane to move to. Cloak's real strength is that he's great for mindgames though. Sometimes your opponent will think you're telegraphing your next play with him, but the nice part about his mechanic is that it's vague. Remember he only gives you the option to move your cards. Nothing says you have to maximize the effect, or even use it at all.
Nakia - I bet she seems like a weird choice, but she's proven pretty valuable. She makes Human Torch a LOT better, if you can manage your hand well enough, and in general allows you to pump up some of your weaker cards which can really help you pull some wins out of your ass. She, however, is also replaceable. Forge, Hulk Buster, Multiple Man, or Okoye are all good options, in addition to your usual toolbox cards like Scorpion or Iceman.
Heimdall - Heimdall is probably my favorite card in the game, and even though he sometimes feels kinda meh in a movement deck like this, I still think he's a sleeper S tier card in non-movement decks where your opponent isn't expecting him (seriously, try it one day, it's crazy how well it can work). I wouldn't necessarily recommend it, but I do think Heimdall is replaceable if, and ONLY if, you have Magneto. With Magneto in the deck, I think you could replace Heimdall with something else, though I'm not sure what. Maybe a utility card like Magik, Leech, Shang Chi, etc., or just a big boi like Red Skull or something. I haven't piloted this deck in higher ranks yet as the season just started, so it remains to be seen if Heimdall remains consistent or if I'll need to replace him with Spikier cards.
In this deck, so far, I really like the dichotomy between Heimdall and Magneto. On the one hand, you can choose to move all of your cards to the left (except Heimdall himself which takes some big brain thinking sometimes), which can be extremely powerful with Vulture, Kraven, and Johnny in there. It also allows you to shift your cards into an unused location, or a location your opponent abandoned, or you pretended to abandon, for a surprise win. On the other hand you can opt to play Magneto and move your opponent's cards to a new location, which can be devastating if played right, for example against the Venom + Arnim Zola deck I've been running into a lot lately (which Magneto often singlehandedly destroys). Having this flexibility is what I believe is the key to the deck's success; rather than being stuck moving all your cards turn 6, you have another option that disrupts your oppoenent instead, which makes the archetype much stronger than it would be otherwise.
Finally, let's talk about the cards that are conspicuously missing:
Doctor Strange - As strange as it may sound (pun intended) I find ol' Steve-O is a lot like Cerebro. He sounds great on paper, but at the end of the day actually using him is awkward. You have to control the power of your cards to use him right, and if you're able to he still pulls them all into his lane, leaving you vulnerable to Shang Cheese. In general, I think that, while he fits mechanically and thematically, he doesn't belong in this deck. His spot is much better filled by Polaris or even Juggernaut in my opinion. He does have the advantage of being one of the few cards that can move a card to the right, though, so he's got that going for him.
Hulk Buster - While I like Hulk Buster a lot, and I love some of the shenanigans you can pull with it and Iron Fist, I find it slow and quite awkward to use. Most of the time you have to do something like Vulture > Iron Fist + Hulk Buster which only gets you 4 more power on Vulture, when you could have just played Iron Fist > Vulture to get the +5, and then played another card turn 4 to just move Vulture again. Also, only one of the cards that HB is good with is in the deck, and that's Human Torch who, again, is highly replaceable and even if he wasn't, I kind of prefer being able to buff him with Nakia instead. Speaking of cards HB is good with...
Multiple Man - I really like this card. Like, a lot. But while playing this deck, I found that Multiple Man was often a dead draw. He needs to be buffed to be good, which means playing Hulk Buster or getting him in the right place in your hand to use Nakia, or throwing in Forge, or something like that. He also clogs up your board in a way that ends up being annoying unless he's basically the best card you have and having multiple copies is actually useful.
I feel like there is a version of this deck where you could use these three, since Dr. Strangecan be decent if you have a high power Multiple Man in 2 lanes, but I just didn't think the deck really worked as well with them in it.