Disallow

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

God-Eternal Kefnet

Flying
You may reveal the first card you draw each turn as you draw it. Whenever you reveal an instant or sorcery card this way, copy that card and you may cast the copy. That copy costs {2} less to cast.
When God-Eternal Kefnet dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Naban, Dean of Iteration

If a Wizard you control entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Agent of Treachery

When Agent of Treachery enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Flux Channeler

Whenever you cast a noncreature spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Pithing Needle

As Pithing Needle enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.

In Bolas's Clutches

Enchant permanent
You control enchanted permanent.
Enchanted permanent is legendary.

Withdraw

Return target creature to its owner's hand. Then return another target creature to its owner's hand unless its controller pays {1}.

Spirit Away

Enchant creature
You control enchanted creature.
Enchanted creature gets +2/+2 and has flying.

Gulf Squid

When Gulf Squid enters, tap all lands target player controls.

Leyline of Anticipation

If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.

Polymorphist's Jest

Until end of turn, each creature target player controls loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Alexi's Cloak

Flash
Enchant creature
Enchanted creature has shroud. (It can't be the target of spells or abilities.)

Skyline Cascade

Skyline Cascade enters tapped.
When Skyline Cascade enters, target creature an opponent controls doesn't untap during its controller's next untap step.
{T}: Add {U}.

Stolen Goods

Target opponent exiles cards from the top of their library until they exile a nonland card. Until end of turn, you may cast that card without paying its mana cost.

Memorial to Genius

Memorial to Genius enters tapped.
{T}: Add {U}.
{4}{U}, {T}, Sacrifice Memorial to Genius: Draw two cards.

Narset, Parter of Veils

Each opponent can't draw more than one card each turn.
−2: Look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Mu Yanling, Sky Dancer

+2: Until your next turn, up to one target creature gets -2/-0 and loses flying.
−3: Create a 4/4 blue Elemental Bird creature token with flying.
−8: You get an emblem with "Islands you control have '{T}: Draw a card.'"

Sunken Field

Enchant land
Enchanted land has "{T}: Counter target spell unless its controller pays {1}."

Psychic Rebuttal

Counter target instant or sorcery spell that targets you.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, you may copy the spell countered this way. You may choose new targets for the copy.

Contentious Plan

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

Release to the Wind

Exile target nonland permanent. For as long as that card remains exiled, its owner may cast it without paying its mana cost.

Lazotep Plating

Amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)
You and permanents you control gain hexproof until end of turn. (You and they can't be the targets of spells or abilities your opponents control.)

Firemind Vessel

Firemind Vessel enters tapped.
{T}: Add two mana of different colors.

Keiga, the Tide Star

Flying
When Keiga, the Tide Star dies, gain control of target creature.

Kasmina, Enigmatic Mentor

Spells your opponents cast that target a creature or planeswalker you control cost {2} more to cast.
−2: Create a 2/2 blue Wizard creature token. Draw a card, then discard a card.

Omnispell Adept

{2}{U}, {T}: You may cast an instant or sorcery spell from your hand without paying its mana cost.

Island

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Zhalfirin Void

When Zhalfirin Void enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {C}.

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Finale of Revelation

Draw X cards. If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game.
Exile Finale of Revelation.

Crafty Cutpurse

Flash
When Crafty Cutpurse enters, each token that would be created under an opponent's control this turn is created under your control instead.

Mass Manipulation

Gain control of X target creatures and/or planeswalkers.

Mana Geode

When Mana Geode enters, scry 1.
{T}: Add one mana of any color.

Spellseeker

When Spellseeker enters, you may search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.