Flying Octobot

Flying
Whenever another Villain you control enters, put a +1/+1 counter on this creature. This ability triggers only once each turn.

Doc Ock's Henchmen

Flash
Whenever this creature attacks, it connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

Lady Octopus, Inspired Inventor

Whenever you draw your first or second card each turn, put an ingenuity counter on Lady Octopus.
{T}: You may cast an artifact spell from your hand with mana value less than or equal to the number of ingenuity counters on Lady Octopus without paying its mana cost.

Prowler, Clawed Thief

Menace (This creature can't be blocked except by two or more creatures.)
Whenever another Villain you control enters, Prowler connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

Swamp

Morbius the Living Vampire

Flying, vigilance, lifelink
{U}{B}, Exile this card from your graveyard: Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Mysterio's Phantasm

Flying, vigilance
Whenever this creature attacks, mill a card. (Put the top card of your library into your graveyard.)

Grendel, Spawn of Knull

Flying (This creature can't be blocked except by creatures with flying or reach.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Mysterio, Master of Illusion

When Mysterio enters, create a 3/3 blue Illusion Villain creature token for each nontoken Villain you control. Exile those tokens when Mysterio leaves the battlefield.

Island

Doctor Doom

When Doctor Doom enters, create two 3/3 colorless Robot Villain artifact creature tokens named Doombot.
As long as you control an artifact creature or a Plan, Doctor Doom has indestructible.
At the beginning of your end step, you draw a card and lose 1 life.

Swarm, Being of Bees

Flash
Flying
Mayhem {B} (You may cast this card from your graveyard for {B} if you discarded it this turn. Timing rules still apply.)

Doc Ock, Evil Inventor

At the beginning of combat on your turn, target noncreature artifact you control becomes an 8/8 Robot Villain artifact creature in addition to its other types.

Doctor Octopus, Master Planner

Other Villains you control get +2/+2.
Your maximum hand size is eight.
At the beginning of your end step, if you have fewer than eight cards in hand, draw cards equal to the difference.

Morlun, Devourer of Spiders

Lifelink
Morlun enters with X +1/+1 counters on him.
When Morlun enters, he deals X damage to target opponent.

Baron Helmut Zemo

Whenever you cast a black spell from your hand, Baron Helmut Zemo connives.
Boast — Exile any number of black cards from your graveyard with fifteen or more black mana symbols among their mana costs: Copy those exiled cards. You may cast up to three of the copies without paying their mana costs. (Activate only if this creature attacked this turn and only once each turn.)

Doc Ock, Sinister Scientist

As long as there are eight or more cards in your graveyard, Doc Ock has base power and toughness 8/8.
As long as you control another Villain, Doc Ock has hexproof. (He can't be the target of spells or abilities your opponents control.)

Tombstone, Career Criminal

When Tombstone enters, return target Villain card from your graveyard to your hand.
Villain spells you cast cost {1} less to cast.

Scorpion, Seething Striker

Deathtouch
At the beginning of your end step, if a creature died this turn, target creature you control connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on that creature.)

Venom, Eddie Brock

Menace (This creature can't be blocked except by two or more creatures.)
Whenever another creature dies, put a +1/+1 counter on Venom. If that creature was a Villain, draw a card.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Black Cat, Cunning Thief

When Black Cat enters, look at the top nine cards of target opponent's library, exile two of them face down, then put the rest on the bottom of their library in a random order. You may play the exiled cards for as long as they remain exiled. Mana of any type can be spent to cast spells this way.

Chameleon, Master of Disguise

You may have Chameleon enter as a copy of a creature you control, except his name is Chameleon, Master of Disguise.
Mayhem {2}{U} (You may cast this card from your graveyard for {2}{U} if you discarded it this turn. Timing rules still apply.)

Sol Ring

Vulture, Scheming Scavenger

Flying
Whenever Vulture attacks, other Villains you control gain flying until end of turn.