Riddleform

Whenever you cast a noncreature spell, you may have Riddleform become a 3/3 Sphinx creature with flying in addition to its other types until end of turn.
{2}{U}: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Divination

Goldvein Pick

Equipped creature gets +1/+1.
Whenever equipped creature deals combat damage to a player, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Wormhole Serpent

{3}{U}: Target creature can't be blocked this turn.

Letter of Acceptance

{T}: Add one mana of any color.
{2}, {T}, Sacrifice Letter of Acceptance: Draw a card.

Memory Lapse

Counter target spell. If that spell is countered this way, put it on top of its owner's library instead of into that player's graveyard.

Kiora's Dambreaker

When Kiora's Dambreaker enters the battlefield, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Capture Sphere

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
When Capture Sphere enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Bone to Ash

Counter target creature spell.
Draw a card.

Tezzeret's Gambit

({U/P} can be paid with either {U} or 2 life.)
Draw two cards, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Annul

Counter target artifact or enchantment spell.

Rescuer Sphinx

Flying
As Rescuer Sphinx enters the battlefield, you may return a nonland permanent you control to its owner's hand. If you do, Rescuer Sphinx enters the battlefield with a +1/+1 counter on it.

Contentious Plan

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Vantress Paladin

Flying
Adamant — If at least three blue mana was spent to cast this spell, Vantress Paladin enters the battlefield with a +1/+1 counter on it.

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Callaphe, Beloved of the Sea

Callaphe's power is equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
Creatures and enchantments you control have "Spells your opponents cast that target this permanent cost {1} more to cast."

Deny the Divine

Counter target creature or enchantment spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Convolute

Counter target spell unless its controller pays {4}.

Kitesail Skirmisher

Flying
Whenever Kitesail Skirmisher attacks, another target creature attacking the same player or planeswalker gains flying until end of turn.
Encore {4}{U} ({4}{U}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Air Servant

Flying
{2}{U}: Tap target creature with flying.

Academy Drake

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Flying
If Academy Drake was kicked, it enters the battlefield with two +1/+1 counters on it.

Halcyon Glaze

Whenever you cast a creature spell, Halcyon Glaze becomes a 4/4 Illusion creature with flying in addition to its other types until end of turn.

Opaline Unicorn

Spell Rupture

Counter target spell unless its controller pays {X}, where X is the greatest power among creatures you control.

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Roost of Drakes

Kicker {2}{U} (You may pay an additional {2}{U} as you cast this spell.)
When Roost of Drakes enters the battlefield, if it was kicked, create a 2/2 blue Drake creature token with flying.
Whenever you cast a kicked spell, create a 2/2 blue Drake creature token with flying.

Spell Satchel

Magecraft — Whenever you cast or copy an instant or sorcery spell, put a book counter on Spell Satchel.
{T}, Remove a book counter from Spell Satchel: Add {C}.
{3}, {T}, Remove three book counters from Spell Satchel: Draw a card.

Anticognition

Counter target creature or planeswalker spell unless its controller pays {2}. If an opponent has eight or more cards in their graveyard, instead counter that spell, then scry 2.

Vodalian Arcanist

{T}: Add {C}. Spend this mana only to cast an instant or sorcery spell.

Counter target spell. That spell's controller may draw a card.

Deep Freeze

Enchant creature
Enchanted creature has base power and toughness 0/4, has defender, loses all other abilities, and is a blue Wall in addition to its other colors and types.

Silver-Inlaid Dagger

Equipped creature gets +2/+0.
As long as equipped creature is a Human, it gets an additional +1/+0.
Equip {2}

Prying Blade

Equipped creature gets +1/+0.
Whenever equipped creature deals combat damage to a player, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Sleep

Tap all creatures target player controls. Those creatures don't untap during that player's next untap step.

Seer's Lantern

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

Karfell Harbinger

{T}: Add {U}. Spend this mana only to foretell a card from your hand or cast an instant or sorcery spell.

Spectral Searchlight

{T}: Choose a player. That player adds one mana of any color they choose.

Put Away

Counter target spell. You may shuffle up to one target card from your graveyard into your library.

Island

Thunder Drake

Flying
Whenever you cast your second spell each turn, put a +1/+1 counter on Thunder Drake.

Kasmina's Transmutation

Enchant creature
Enchanted creature loses all abilities and has base power and toughness 1/1.

Dismiss

Statute of Denial

Counter target spell. If you control a blue creature, draw a card, then discard a card.

Avian Oddity

Flying
Cycling {2}{U} ({2}{U}, Discard this card: Draw a card.)
When you cycle Avian Oddity, put a flying counter on target creature you control.

Spell Snuff

Counter target spell.
Fateful hour — If you have 5 or less life, draw a card.

Mana Leak

Counter target spell unless its controller pays {3}.

Whirlwind Adept

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Ichthyomorphosis

Enchant creature
Enchanted creature loses all abilities and is a blue Fish with base power and toughness 0/1.

Reject

Counter target creature or planeswalker spell unless its controller pays {3}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Time of Ice

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Tap target creature an opponent controls. It doesn't untap during its controller's untap step for as long as you control Time of Ice.
III — Return all tapped creatures to their owners' hands.

True-Faith Censer

Equipped creature gets +1/+1 and has vigilance.
As long as equipped creature is a Human, it gets an additional +1/+0.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Flash Counter

Clinging Anemones

Defender
Evolve (Whenever a creature enters the battlefield under your control, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Keep Safe

Counter target spell that targets a permanent you control.
Draw a card.

Air Elemental

Iceberg

Iceberg enters the battlefield with X ice counters on it.
{3}: Put an ice counter on Iceberg.
Remove an ice counter from Iceberg: Add {C}.

Revolutionary Rebuff

Counter target nonartifact spell unless its controller pays {2}.

Negate

Spiketail Drakeling

Flying
Sacrifice Spiketail Drakeling: Counter target spell unless its controller pays {2}.

Cancel

Relentless Skaabs

As an additional cost to cast this spell, exile a creature card from your graveyard.
Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Code of Constraint

Target creature gets -4/-0 until end of turn.
Draw a card.
Addendum — If you cast this spell during your main phase, tap that creature and it doesn't untap during its controller's next untap step.

Naiad of Hidden Coves

As long as it's not your turn, spells you cast cost {1} less to cast.

Steady Progress

Skitter Eel

{2}{U}: Adapt 2. (If this creature has no +1/+1 counters on it, put two +1/+1 counters on it.)