Reweave

Target permanent's controller sacrifices it. If the player does, they reveal cards from the top of their library until they reveal a permanent card that shares a card type with the sacrificed permanent, put that card onto the battlefield, then shuffle.
Splice onto Arcane {2}{U}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Murmurs from Beyond

Reveal the top three cards of your library. An opponent chooses one of them. Put that card into your graveyard and the rest into your hand.

Crushing Pain

Crushing Pain deals 6 damage to target creature that was dealt damage this turn.

Disrupting Shoal

You may exile a blue card with mana value X from your hand rather than pay this spell's mana cost.
Counter target spell if its mana value is X.

Eye of Nowhere

Return target permanent to its owner's hand.

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Winds of Change

Each player shuffles the cards from their hand into their library, then draws that many cards.

Consuming Vortex

Return target creature to its owner's hand.
Splice onto Arcane {3}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Through the Breach

You may put a creature card from your hand onto the battlefield. That creature gains haste. Sacrifice that creature at the beginning of the next end step.
Splice onto Arcane {2}{R}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Wear Away

Destroy target artifact or enchantment.
Splice onto Arcane {3}{G} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Kodama's Might

Target creature gets +2/+2 until end of turn.
Splice onto Arcane {G} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Reach Through Mists

Ideas Unbound

Draw three cards. Discard three cards at the beginning of the next end step.

Psychic Puppetry

You may tap or untap target permanent.
Splice onto Arcane {U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Glacial Ray

Glacial Ray deals 2 damage to any target.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Peer Through Depths

Look at the top five cards of your library. You may reveal an instant or sorcery card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Eerie Procession

Search your library for an Arcane card, reveal that card, put it into your hand, then shuffle.

Into the Fray

Target creature attacks this turn if able.
Splice onto Arcane {R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Roar of Jukai

If you control a Forest, each blocked creature gets +2/+2 until end of turn.
Splice onto Arcane—An opponent gains 5 life. (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Toils of Night and Day

You may tap or untap target permanent, then you may tap or untap another target permanent.

Rending Vines

Destroy target artifact or enchantment if its mana value is less than or equal to the number of cards in your hand.
Draw a card.

Shifting Borders

Exchange control of two target lands.
Splice onto Arcane {3}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Riku of Two Reflections

Whenever you cast an instant or sorcery spell, you may pay {U}{R}. If you do, copy that spell. You may choose new targets for the copy.
Whenever another nontoken creature you control enters, you may pay {G}{U}. If you do, create a token that's a copy of that creature.

The Unspeakable

Flying, trample
Whenever The Unspeakable deals combat damage to a player, you may return target Arcane card from your graveyard to your hand.

Inner Calm, Outer Strength

Target creature gets +X/+X until end of turn, where X is the number of cards in your hand.

Lava Spike

Lava Spike deals 3 damage to target player or planeswalker.

Sift Through Sands

Draw two cards, then discard a card.
If you've cast a spell named Peer Through Depths and a spell named Reach Through Mists this turn, you may search your library for a card named The Unspeakable, put it onto the battlefield, then shuffle.

Blazing Shoal

You may exile a red card with mana value X from your hand rather than pay this spell's mana cost.
Target creature gets +X/+0 until end of turn.

Crack the Earth

Each player sacrifices a permanent of their choice.

Overblaze

Each time target permanent would deal damage to a permanent or player this turn, it deals double that damage to that permanent or player instead.
Splice onto Arcane {2}{R}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Strange Inversion

Switch target creature's power and toughness until end of turn.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Veil of Secrecy

Target creature gains shroud until end of turn and can't be blocked this turn. (A creature with shroud can't be the target of spells or abilities.)
Splice onto Arcane—Return a blue creature you control to its owner's hand. (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Evermind

(Nonexistent mana costs can't be paid.)
Draw a card.
Splice onto Arcane {1}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)