Carnage Altar

Artifact

, Sacrifice a creature: Draw a card.

Catalyst Stone

Artifact

Flashback costs you pay cost up to less.
Flashback costs your opponents pay cost more.

Charcoal Diamond

Artifact

Charcoal Diamond enters the battlefield tapped.
: Add .

Cloak and Dagger

Tribal Artifact — Rogue Equipment

Equipped creature gets +2/+0 and has shroud. (It can't be the target of spells or abilities.)
Whenever a Rogue creature enters the battlefield, you may attach Cloak and Dagger to it.
Equip

Cloak of the Bat

Artifact — Equipment

Equipped creature has flying and haste.
Equip (: Attach to target creature you control. Equip only as a sorcery.)

Cobbled Wings

Artifact — Equipment

Equipped creature has flying.
Equip (: Attach to target creature you control. Equip only as a sorcery.)

Cogworker's Puzzleknot

Artifact

When Cogworker's Puzzleknot enters the battlefield, create a 1/1 colorless Servo artifact creature token.
, Sacrifice Cogworker's Puzzleknot: Create a 1/1 colorless Servo artifact creature token.

Coldsteel Heart

Snow Artifact

Coldsteel Heart enters the battlefield tapped.
As Coldsteel Heart enters the battlefield, choose a color.
: Add one mana of the chosen color.

Collector's Vault

Artifact

, : Draw a card, then discard a card. Create a Treasure token. (It's an artifact with ", Sacrifice this artifact: Add one mana of any color.")

Consulate Skygate

Artifact Creature — Wall (0/4)

Defender
Reach (This creature can block creatures with flying.)

Copper Myr

Artifact Creature — Myr (1/1)

: Add .

Copper Tablet

Artifact

At the beginning of each player's upkeep, Copper Tablet deals 1 damage to that player.

Corrupted Grafstone

Artifact

Corrupted Grafstone enters the battlefield tapped.
: Choose a color of a card in your graveyard. Add one mana of that color.

Cranial Archive

Artifact

, Exile Cranial Archive: Target player shuffles their graveyard into their library. Draw a card.

Crown of the Ages

Artifact

, : Attach target Aura attached to a creature to another creature.

Crystalline Crawler

Artifact Creature — Construct (1/1)

Converge — Crystalline Crawler enters the battlefield with a +1/+1 counter on it for each color of mana spent to cast it.
Remove a +1/+1 counter from Crystalline Crawler: Add one mana of any color.
: Put a +1/+1 counter on Crystalline Crawler.

Cultist's Staff

Artifact — Equipment

Equipped creature gets +2/+2.
Equip (: Attach to target creature you control. Equip only as a sorcery.)

Curious Killbot

Artifact Creature — Killbot (2/1)

Cursed Totem

Artifact

Activated abilities of creatures can't be activated.

Cybermat

Artifact Creature — Robot (2/1)

Skulk (This creature can't be blocked by creatures with greater power.)
Whenever Cybermat attacks and isn't blocked, it gets +X/+0 until end of turn, where X is the number of attacking artifact creatures.