Whenever a creature you control deals combat damage to a player, you may sacrifice it. If you do, draw a card. Otherwise, surveil 1.

Choose one —
• Return target creature card from a graveyard to its owner's hand.
• Exile target creature card in a graveyard, then draw a card.

Choose up to X target creatures. Switch their power and toughness until end of turn.
All creatures get -3/-3 until end of turn.

{T}: Add {C}.
{1}, {T}, Sacrifice Cradle of Rebirth: Copy target spell you control which had its flashback cost paid. You may choose new targets for the copy.

{T}: Add one mana of any color.
{T}: Draw a card, then discard a card. Activate only if you've cast a non-Human creature spell this turn.

Gain control of target permanent. Untap it. It gains haste until end of turn.

Exile target creature with flying.

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.

Destroy target creature. Create two Berry tokens.

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.”

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

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.

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.

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.

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

Return target permanent card with an activated ability from your graveyard to the battlefield. You may activate its abilities this turn as though it had haste.

Target player discards two cards. Exile their graveyard.

Exile all creatures and all cards from each player's hand. Any player may play those cards during their turn for as long as they remain exiled, and mana of any type can be spent to cast those spells.
Exile Dawn of Peace.