MTG Karumonix, the Rat King Deck by MTGA-Assistant-Meta

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.) Other Rats you control have toxic 1. When Karumonix enters, look at the top five cards of your library. You may reveal any number of Rat cards from among them and put the revealed cards into your hand. Put the rest on the bottom of your library in a random order.

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Ninjutsu {1}{B} ({1}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) When Nezumi Prowler enters, put a deathtouch counter and a lifelink counter on target creature you control.

When this creature enters, each opponent discards a card.

Pack Rat's power and toughness are each equal to the number of Rats you control. {2}{B}, Discard a card: Create a token that's a copy of this creature.

Rats you control have menace. {1}{B}, {T}: Create a 1/1 black Rat creature token. {2}{B}{B}, {T}, Sacrifice three Rats: Gain control of target creature.

This creature gets +1/+0 for each other Rat you control. A deck can have any number of cards named Rat Colony.

This creature can't block. When this creature dies, create X 1/1 black Rat creature tokens with "This token can't block," where X is the amount of damage dealt to it this turn.

Whenever another Rat you control enters, exile up to one target card from an opponent's graveyard. At the beginning of combat on your turn, create a 1/1 black Rat creature token with "This token can't block."

Ninjutsu {2}{B} ({2}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.) Whenever Nashi, Moon Sage's Scion deals combat damage to a player, exile the top card of each player's library. Until end of turn, you may play one of those cards. If you cast a spell this way, pay life equal to its mana value rather than paying its mana cost.

Deathtouch Whenever you draw a card, you gain 2 life. Whenever an opponent draws a card, they lose 2 life.

All Rats have fear. {T}, Sacrifice a Rat: Create X 1/1 black Rat creature tokens, where X is the number of Rats you control.

This creature can't block. When this creature enters, if you cast it from your hand, it deals 1 damage to target opponent for each Swamp you control.

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

As this artifact enters, choose a creature type. Creature spells you cast of the chosen type cost {1} less to cast. At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

As this artifact enters, choose a color. Creatures you control of the chosen color get +1/+0. {T}: Add one mana of the chosen color.

As this artifact enters, choose a creature type. Creatures you control of the chosen type get +1/+1. Whenever you cast a creature spell of the chosen type, draw a card.

Destroy target creature with total power and toughness 5 or less.

Destroy target nonartifact creature.

Destroy target creature. You lose 2 life.

Each opponent sacrifices a creature or planeswalker with the greatest mana value among creatures and planeswalkers they control.

Destroy target creature.

Target player reveals their hand. You choose a nonland card from it. That player discards that card. You lose 2 life.

Destroy target creature or planeswalker. Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Corrupt deals damage to any target equal to the number of Swamps you control. You gain life equal to the damage dealt this way.

({T}: Add {B}.) Gate of the Black Dragon enters the battlefield tapped. {3}{B}, {T}: Seek a nonland card. Activate only once.

({T}: Add {B}.)

{T}: Add {B}. Channel — {3}{B}, Discard this card: Mill three cards, then return a creature or planeswalker card from your graveyard to your hand. This ability costs {1} less to activate for each legendary creature you control.

As this land enters, choose a creature type. {T}: Add {C}. {T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

As Three Tree City enters, choose a creature type. {T}: Add {C}. {2}, {T}: Choose a color. Add an amount of mana of that color equal to the number of creatures you control of the chosen type.