Captain America, Team Leader

Whenever another Hero you control enters, it gains vigilance and haste until end of turn. Put a +1/+1 counter on that Hero and a +1/+1 counter on Captain America.

Namor, Atlantean King

Merfolk

Flying
Whenever you cast a noncreature spell, create a 1/1 blue Merfolk creature token.
Whenever Namor attacks a player who has more life than you, other creatures you control attacking that player get +2/+0 until end of turn.

Doctor Doom, King of Latveria

Whenever you discard one or more land cards, each opponent loses 2 life.
At the beginning of combat on your turn, target Villain you control gains menace until end of turn. It connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on that creature.)

Vibranium

T'Challa, the Black Panther

Whenever T'Challa enters or attacks, create a tapped Vibranium token. (It's an artifact with indestructible and "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")
Whenever you cast an artifact spell with mana value 4 or greater, put two +1/+1 counters on T'Challa.

Rescue, Pepper Potts

Flash
Flying
When Rescue enters, return up to one other target artifact or creature you control to its owner's hand. If it was an artifact, put a +1/+1 counter on Rescue.

Thor, Asgard's Avenger

Flying
If another source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 1 instead.

Okoye, Mighty and Adored

When Okoye enters, you become the monarch.
At the beginning of combat on your turn, put a +1/+1 counter on target creature. Whenever that creature attacks the monarch this turn, it gains double strike and trample until end of turn.

Molecule Man

Nonland cards in your hand have miracle {0}. (You may cast a card for its miracle cost when you draw it if it's the first card you drew this turn.)

Power Pack

Flying, vigilance, trample, haste
Whenever Power Pack deals combat damage to a player, exile target instant or sorcery card from your graveyard chosen at random. At the beginning of your next upkeep, you may cast that card without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Quicksilver, Speedster

Flash
Double strike, haste
As long as Quicksilver is tapped, you may cast spells as though they had flash.

Ape Villain

Red Ghost, Intangible Genius

Ward {2}
Red Ghost can't be blocked.
Whenever you draw your second card each turn, create a 3/3 red Ape Villain creature token with haste.

Scarlet Witch, Chaotic Avenger

Flying
Whenever Scarlet Witch deals combat damage to a player, look at the top two cards of your library, then exile them face down. Then you may cast a Hero or noncreature spell from among cards exiled with Scarlet Witch without paying its mana cost.

Shang-Chi and the Ten Rings

First strike
Whenever you draw a card, put a +1/+1 counter on Shang-Chi.
When the tenth +1/+1 counter is put on Shang-Chi, you draw five cards and gain 5 life.

Shuri, the Black Panther

Lifelink
Whenever Shuri attacks, draw a card if you control three or more artifacts. Then if you control six or more artifacts, creatures you control get +2/+2 until end of turn.

The Squadron Sinister

Flying, haste
Other Villains you control get +2/+2 and have flying and haste.
Mayhem {3}{U}{R} (You may cast this card from your graveyard for {3}{U}{R} if you discarded it this turn. Timing rules still apply.)

Storm, Queen of Wakanda

Flying
Whenever Storm attacks, until end of turn, another target attacking creature gains flying and gets +X/+0, where X is Storm's power.
Whenever a creature with flying attacks you, Storm deals damage equal to her power to that creature.

Marvel Super Heroes Commander