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.

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

Landfall — Whenever a land you control enters, exile the top card of your library. You may play that card until the end of your next turn.
{1}{R}, Sacrifice Crumbling Tower: It deals damage equal to the number of cards exiled with it to target player.

[+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.”

Cryptic Reef enters tapped.
{T}: Add {G} or {U}.
{2}{G}{U}, {T}, Sacrifice Cryptic Reef: Draw a card.

When Cryptolabe enters, draw a card. Then exile a card from your hand. You may play that card for as long as they remain exiled.
{T}: Add {G}{U}. This mana can't be spent to cast spells from your hand.

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}

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.

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.

Dark Horizon enters tapped.
{T}: Add {C} or {B}.
{1}, Discard Dark Horizon: Scry 2.

When Data Weaver enters, integrate the top two cards of target opponent's library.
Once during each of your turns, you may play a card integrated onto a permanent you control, and mana of any type can be spent to cast it.

First strike
Whenever Dated Mechanoid becomes tapped, another target creature you control gets +1/+1 until end of turn.

Ward {3}
Daunting Snapper can't be blocked by creatures with power 2 or less.

Flying
When Daybreak Rider enters, you may bless another target creature.

Whenever another artifact you control enters, Dazzling Illuminator can't be blocked this turn.

Ward {2}
Amity — Whenever you attack with Dazzling Performer and exactly one other creature, put a +1/+1 counter on each of those creatures. Until end of turn, they gain trample and “Whenever this creature deals combat damage to a player, draw a card.”

{6}, {T}, Sacrifice Deafening Loudspeaker: It deals 5 damage to target creature. This ability costs {1} less to activate for each attacking creature you control.

When Deathcap Guardian enters, exile any number of permanent cards from your graveyard. When you do, put X +1/+1 counters on Deathcap Guardian and up to one target creature gets -X/-X until end of turn, where X is the number of cards exiled this way.