msem-instigator

{T}: Mill three cards. Scry 1.
{1}, Sacrifice Consecrated Altar: Counter target spell or ability that targets you or one or more cards in your graveyard.

{T}: Add {C}.
{T}, Sacrifice a Clue: Draw a card.

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/-1.
Whenever equipped creature dies, draw a card. This ability triggers only once each turn.
Equip {1}

{T}: Add one mana of any color.
{5}, {T}, Sacrifice Cosmic Chart: Search your library for a card, put it into your hand, then shuffle.

Whenever you cast a spell, you may pay 3 life. If you do, draw a card.

Equipped creature gets +2/+1.
Whenever equipped creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability.
Equip {2}

{T}: Add one mana of any color.
{3}, {T}, Sacrifice Coveted Heirloom: Draw a card.
Tap three untapped artifacts you control: Return Coveted Heirloom from your graveyard to the battlefield.

Cradle of War enters tapped.
{3}, {T}: You may put an artifact card with mana value 3 or less from your hand onto the battlefield. This ability costs {1} less to activate for each other artifact you control. Activate only as a sorcery.

Equipped creature gets +2/+0 and has flying.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

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

Flash
When Cranial Glass enters, exile target card from a graveyard.
{7}, {T}, Sacrifice Cranial Glass: Copy the exiled card. You may cast the copy without paying its mana cost. (A copy of a permanent spell becomes a token.)

{T}: Add {C}.
{3}, {T}: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

You may have Crossroads Town enter tapped. If you do, search your library for a basic land card, reveal it, then shuffle and put that card on top.
{T}: Add {C}.

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell with a creature type no creature you control has.

You may play lands from your graveyard.

{2}, {T}: Draw a card. Crude Tablet doesn't untap during its controller's next untap step.

Reach
Scarecrow spells you cast cost {1} less to cast.

Whenever Cruising Schooner attacks, it gets +1/+1 until end of turn.
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

Crumbling Vestige enters tapped.
When Crumbling Vestige enters, add one mana of any color.
{T}: Add {C}.

When Crux Pinnacle enters, for each color, exile up to one target permanent of that color until Crux Pinnacle leaves the battlefield.
Whenever a player casts a spell, if there are five or more spells on the stack, you win the game.

{T}: Add {C}.
{X}: Crypt of Myriad Fates becomes a copy of target creature card with mana value X or less in your graveyard until end of turn, except it's 2/2 and a land in addition to its other types. Activate only outside of combat.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{1}, Discard two cards: Unlock Cryptic Fragment. If the revealed card is a basic land card, put it into your hand.

Whenever you sacrifice a permanent, scry 1.
{1}, Sacrifice a nonland permanent: You gain 1 life.

Crystal Garden enters tapped.
{T}: Add one mana of any color. You can't spend this mana to cast a creature spell.