These cards are only available from the Marvel 3D Trading Cards Packs sold in 2015.

They don't make them anymore.

The packs came with 5 cards, 3 3D non-playable cards of Legendary characters and 2 random playable cards. So the buyer had a random chance of getting 2 of the 98 playable cards. There was also a rare chance of a sketch card.

So after buying lots of packs, one might have enough to have a whole set of a hero, henchman or bystander set.

These trading card packs are the only way to get 3 alternate art 14-card Hero decks from the base game (Black Widow, Deadpool, and Hulk), 2 14-card exclusive Heros sets (Howard the Duck and Man-Thing), 2 10-card Henchmen decks (Circus of Crime, Spider-Slayer), and 1 5-card Bystander deck (Bulldoze Driver, Double Agent of Shield, Fortune Teller, Photographer, Stan Lee).

The complete set includes:

Black Widow Deck (14 cards, Alternate-Art, Hero) = 1 Rare Silent Sniper, 3 Uncommon Covert Operation, 5 Common Dangerous Rescue, 5 Common Mission Accomplished

Deadpool Deck (14 cards, Alternate-Art, Hero) = 1 Rare Random Acts of Unkindness, 3 Uncommon Hey, Can I get a Do-over, 5 Common Oddball, 5 Common Here Hold This For a Minute

Hulk Deck (14 cards, Alternate-Art, Hero) = 1 Rare Hulk Smash, 3 Uncommon Crazed Rampage, 5 Common Unstoppable Hulk, 5 Common Growing Anger

Howard the Duck Deck (14 cards, Hero) = 1 Rare Interplanetary Visitor, 3 Uncommon Right Place, Wrong Time, 5 Common Traveling Companion, 5 Common Rebel Without a Cause

Man-Thing Deck (14 cards, Hero) = 1 Rare Eternity of Solitude, 3 Uncommon Travel the Nexus of Realities, 5 Common Burn the Fearful, 5 Common Form the Ooze

Circus of Crime (10 cards, Henchman)

Spider-slayer (10 cards, Henchman)

Rare Bulldozer Driver (1 card, Bystander)

Rare Double Agent of Shield (1 card, Bystander)

Rare Fortune Teller (1 card, Bystander)

Rare Photographer (1 card, Bystander)

Uncommon Stan Lee (4 cards, Bystander)