Test deck that focused on locking down lane locations and controlling where your opponent can play. I wouldn't say any card is really essential but Goose, Doom and Spiderman are probably the most important tools. The goal of the deck is to gain priority (thereby winning), then controlling where an opponent's cards go so they cannot come back from it.
Every card kind of has a role, as does every substitution:
SUNSPOT - Soaks any Float you have when you can't play to the curve. As an additional aside, he gives you an extra option that is to NOT play cards and gain power at a location. This can be useful if you've locked down a lane but think an opponent might try to sneak some power over via something like Spectrum or an exploding Nova.
IRON FIST - You're going to be playing cards that limit where you can both play. The difference is that you'll have Iron Fist for utility. Punching things into lanes you've restricted or locations that already have restrictions can be game winning if the opponent doesn't have a deck that has reach.
DAREDEVIL - Gives you a window to prepare for Turn 6 with a counter Turn 5 play or a crippling Turn 5 play. You can obviously parachute Professor X into a safe lane and secure it, but Daredevil also gives you options of playing down other lockdown plays an winning lanes that way.
GOOSE - Combos really well with Iron Fist, Captain Marvel and Doom in this deck. Your opponent can cheat stuff like She-Hulk and Death so be on the lookout for those. Aero can stuff them out if it isn't expected, but not foolproof.
SCARLET WITCH - Use mainly as a rug pull. Opponent sees Nexus and is dumping all his plays there? Wait until Turn 6, then pull the rug from under him with Wanda. You could use Rhino or Storm for safe plays but both cost +1 Energy, which isn't as flexible. SWitch can of course also be used to swap out bad locations for you, most of the time.
MISTER FANTASTIC - Useful at snagging priority and putting pressure on lanes where your opponent doesn't want to play cards in or have restrictions. 2-All isn't very high, but you have other cards you can use to compensate. And if the opponent has a small number of options for reach, Reed's+2 can be game winning.
SPIDERMAN - Locks down a location for 1 turn. Good at dictating which other lane your opponent has to play at. Especially if you've also Goose'd another lane for example. Other times, this can be a straight crippler play and force an opponent to lose a turn. Bad for Turn 6 but playable pretty much anytime before it.
PROFESSOR X - Charles is a bit risky but can be extremely rewarding because he flat out denies an opponent to play anymore cards. They can still effect their power though, so be aware of that. DD into Professor X is classic. But if you can cheat out Professor X due to an opponent or location, you can really surprise the pants off someone and steal a lane for free.
CAPTAIN MARVEL - Just be aware of Captain Marvel's restrictions. Since she can fly into lanes you've shut off yourself, she is a safe play whenever you have the energy to spare. Don't play multiple Captain Marvels though since they basically make the same check at the same time.
AERO - Despite the nerf, Aero is still good at shutting down a Turn 5 play and putting an opponent in a tricky spot. You can also do combos where you use Aero to move cards into a lane you don't want, and have Iron Fist shove over.
DOOM - 15 Power spread across 3 lanes is good. 5 of that power may be superficial, but the coverage makes Doom a safe bet. He also sneaks power into those locations which you've already shut down, so opponents with limited reach are going to be in for a rude awakening if the power difference between location isn't too hight.
MAGNETO - If you're opponents played cards that outpower you at a locked location, you can use Magneto to surprise them by pulling them back out. Other times, Magneto can also be just used as a stat stick. 12 Power is solid.
Your subs:
STORM - As noted, can be a replacement for SWitch, but +1 Cost -1 Power is worse as an overall card play. However, Storm does synergize with the deck theme and she's safer for the same purposes you might normally play SWitch in this deck (rug pulling). Usually not a great Turn 3 play since 2 power is bad and you're likely going to get out muscled though.
KLAW - Adds 6 Power, which isn't nothing, to a location that you might not want to or be able to play at. In general Klaw works as a substitute to Captain Marvel but is less flexible since he can't target to the left. However, in combination with other cards, he can work decently.
DOC OCT - Best played with Iron Fist. If you've played Iron Fist on 4, then Doc Oct on 5 into a lane you don't want can basically force out all of the opponent's options on 6. Some decks (such as this one) cannot play cards indiscriminately. That is to say, they have specific windows or have to be played in order. Doc Oct basically put a wrench on those. You can also combo him with...
HEIMDALL - Can be a big surprise factor here. You're locking locations left and right but then you're not really playing a traditional move deck. They might be expecting a Torch, Dagger or Vulture but not see it. So if you do something like Doc Oct into Heimdall, you can basically make Turn 6 one where your opponent has dumped all their cards into a lane you're abandoning.
QUAKE - Can sub over SWitch, DD or Sunspot. Used primarily similar to SWitch by rug pulling at the last minute.. Nexus has already been mentioned, but can also be done with Bar with No Name, Rickety Bridge, Mojo World, etc. Can be a bit safer than SWitch since you'll know what you're shuffling around but also a bit more limiting too.
NIGHTCRAWLER - Sub over Sunspot. Moving and adding +2 into a lockdown synergizes with the deck. I just don't include it as part of the main deck since it might give a bit too much away.
POLARIS - Magneto can't move 1-2 cards, but Polaris can, so you might consider her a spot alongside Magnet man. Even though she can only move 1, this can help you secure a lane with Goose in it.