Vigilance
Whenever this creature transforms into Crown Betrayer or another permanent you control transforms, Crown Betrayer gets +2/+0 and gains indestructible until end of turn.

As Crownguard Ban enters, choose a card name.
Spells with the chosen name can't be cast.
{3}, Exile a card from your hand with the chosen name: Draw a card. Any player may activate this ability.

{T}: Target creature you control gains menace until end of turn. If it already had menace, it gets +1/+0 until end of turn.

When Crownguard Instructor enters, put a vigilance counter on target creature you control.

Cruiser Technician can't be blocked except by artifact creatures.
Whenever you amp it up, draw two cards, then discard two cards.

The next spell you cast this turn may be cast as though it had flash. When you cast that spell, copy it. You may choose new targets for the copy.
Flashback {3}{U}{U}

Destroy target artifact or land.
Flashback {4}{R}{R}

[+1]: Crux deals 1 damage to target player or planeswalker. Put a chain counter on up to one target artifact or nonbasic land. It loses all abilities except mana abilities as long as it has a chain counter on it.
[–2]: Discard a card. When you do, Crux deals damage equal to the discarded card's mana value to up to one target creature and you draw a card.
[–6]: Exile target red instant or sorcery card from your graveyard. Add {R}{R}{R}, then you get an emblem with “You may cast copies of the exiled card.”

When Cryptolabe enters, exile your hand and the top card of your library. You may play cards exiled this way for as long as they remain exiled.
{T}: Add {G}{U}. This mana can't be spent to cast spells from your hand.

As an additional cost to cast this spell, exile a card from your graveyard.
Search your library for a card with the same mana value as the exiled card, reveal it, put it into your hand, then shuffle. You lose 2 life.

Flash
Haste
When Cuernas, Victor of the Ring enters, it and other legendary creatures you control gain trample and indestructible until end of turn.

Integrate each nontoken creature you don't control with power 2 or less.

Cumulus Soundvein enters tapped.
When Cumulus Soundvein enters, you may pay 1 life. If you do, add one mana of any color other than white.
{T}: Add {W}.

Whenever you attack, if Cursed Claymore entered this turn, attach it to target attacking creature.
Equipped creature gets +2/+1. As long as equipped creature is a Ruin, it's a creature in addition to its other types.
Equip {2}

Destroy target attacking or blocking creature with power 3 or less. Scry 1.

Flash
Whenever you cast a spell during an opponent's turn, scry 1 and put a +1/+1 counter on Cutthroat Kallukah.

When Cutting Room Floor enters, scry 2.
Whenever you scry, you may pay {1}. If you do, target creature gets -X/-X until end of turn, where X is the number of cards you looked at.

Flying
Whenever Cybat becomes tapped, you gain 1 life.

Deathtouch
Ward—Pay 4 life.
Whenever Cybele of the Frozen Faith deals combat damage to a player, you may skip your next turn. If you do, at the beginning of your next turn's upkeep, each opponent discards their hand, you draw seven cards, then put seven +1/+1 counters on Cybele.

Untap all lands you control. Until end of turn, they become 1/1 Elemental artifact creatures with vigilance, indestructible, and haste in addition to their other types.

When D'Enzo Orsino enters, you may search your library for a card named Marie Laurent, a card named Hans Nehmann and a card named Diago Maldovo, reveal them, put them into your hand, then shuffle.
Prevent all combat damage that would be dealt to legendary Allies you control.

Flash
Daggertooth Keelah can't block unless it entered this turn.
{1}{B}, Exile a permanent card from your graveyard: Daggertooth Keelah gains indestructible until end of turn.

Hexproof
When Dakran Shipcrusher enters, you may bless target creature.

Approval — When Dampening Reconciliator enters, tap up to one target creature and put X stun counters on it, where X is the number of colors among permanents you control.

Vigilance
Whenever Dark Ambassador attacks, exile up to one target creature, then return that card to the battlefield tapped under its owner's control.