Legolas's Quick Reflexes

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Untap target creature. Until end of turn, it gains hexproof, reach, and "Whenever this creature becomes tapped, it deals damage equal to its power to up to one target creature."

Protean Hulk

When Protean Hulk dies, search your library for any number of creature cards with total mana value 6 or less, put them onto the battlefield, then shuffle.

Magewright's Stone

{1}, {T}: Untap target creature that has an activated ability with {T} in its cost.

Mental Misstep

({U/P} can be paid with either {U} or 2 life.)
Counter target spell with mana value 1.

Sol Ring

Kiora's Follower

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Quirion Ranger

Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Fatestitcher

{T}: You may tap or untap another target permanent.
Unearth {U} ({U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Arbor Elf

Avenger of Zendikar

When Avenger of Zendikar enters, create a 0/1 green Plant creature token for each land you control.
Landfall — Whenever a land you control enters, you may put a +1/+1 counter on each Plant creature you control.

Instill Energy

Enchant creature
Enchanted creature can attack as though it had haste.
{0}: Untap enchanted creature. Activate only during your turn and only once each turn.

Corridor Monitor

When Corridor Monitor enters, untap target artifact or creature you control.

Craterhoof Behemoth

Haste
When Craterhoof Behemoth enters, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.

Refocus

Great Oak Guardian

Flash (You may cast this spell any time you could cast an instant.)
Reach
When Great Oak Guardian enters, creatures target player controls get +2/+2 until end of turn. Untap them.

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Pestermite

Flash
Flying
When Pestermite enters, you may tap or untap target permanent.

Coiling Oracle

When Coiling Oracle enters, reveal the top card of your library. If it's a land card, put it onto the battlefield. Otherwise, put that card into your hand.

Gift of the Viper

Put a +1/+1 counter, a reach counter, and a deathtouch counter on target creature. Untap it.

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Shore Up

Target creature you control gets +1/+1 and gains hexproof until end of turn. Untap it. (It can't be the target of spells or abilities your opponents control.)

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

Crypsis

Target creature you control gains protection from creatures your opponents control until end of turn. Untap it.

Leaping Ambush

Target creature gets +1/+3 and gains reach until end of turn. Untap it.

Concordant Crossroads

Teardrop Kami

Sacrifice Teardrop Kami: You may tap or untap target creature.

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Counterspell

Chain Stasis

You may tap or untap target creature. Then that creature's controller may pay {2}{U}. If the player does, they may copy this spell and may choose a new target for that copy.

Crashing Drawbridge

Defender
{T}: Creatures you control gain haste until end of turn.

Prime Speaker Vannifar

{T}, Sacrifice another creature: Search your library for a creature card with mana value equal to 1 plus the sacrificed creature's mana value, put that card onto the battlefield, then shuffle. Activate only as a sorcery.

Hapless Researcher

Sacrifice Hapless Researcher: Draw a card, then discard a card.

Leveler

When Leveler enters, exile all cards from your library.

Benefactor's Draught

Untap all creatures. Until end of turn, whenever a creature an opponent controls blocks, draw a card.
Draw a card.

Birds of Paradise

Tribute to the World Tree

Whenever a creature you control enters, draw a card if its power is 3 or greater. Otherwise, put two +1/+1 counters on it.

Forest

Ornamental Courage

Untap target creature. It gets +1/+3 until end of turn.

Body Double

You may have Body Double enter as a copy of any creature card in a graveyard.

Fyndhorn Elves

Timeless Witness

When Timeless Witness enters, return target card from your graveyard to your hand.
Eternalize {5}{G}{G} ({5}{G}{G}, Exile this card from your graveyard: Create a token that's a copy of it, except it's a 4/4 black Zombie Human Shaman with no mana cost. Eternalize only as a sorcery.)

Arachnoid Adaptation

Target creature gets +2/+2 and gains reach until end of turn. Untap it.

Bounding Krasis

Flash (You may cast this spell any time you could cast an instant.)
When Bounding Krasis enters, you may tap or untap target creature.

Peregrine Drake

Flying
When Peregrine Drake enters, untap up to five lands.

Turn Aside

Counter target spell that targets a permanent you control.

Negate

Scryb Ranger

Flash
Flying, protection from blue
Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Veteran Explorer

When Veteran Explorer dies, each player may search their library for up to two basic land cards, put them onto the battlefield, then shuffle.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Woodland Bellower

When Woodland Bellower enters, you may search your library for a nonlegendary green creature card with mana value 3 or less, put it onto the battlefield, then shuffle.

Deceiver Exarch

Flash (You may cast this spell any time you could cast an instant.)
When Deceiver Exarch enters, choose one —
• Untap target permanent you control.
• Tap target permanent an opponent controls.

Elvish Mystic

Emerald Charm

Choose one —
• Untap target permanent.
• Destroy target non-Aura enchantment.
• Target creature loses flying until end of turn.

Loaming Shaman

When Loaming Shaman enters, target player shuffles any number of target cards from their graveyard into their library.

Nature's Chosen

Enchant creature you control
{0}: Untap enchanted creature. Activate only during your turn and only once each turn.
Tap enchanted creature: Untap target artifact, creature, or land. Activate only if enchanted creature is white and untapped and only once each turn.

Viridian Emissary

When Viridian Emissary dies, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Surrak and Goreclaw

Trample
Other creatures you control have trample.
Whenever another nontoken creature you control enters, put a +1/+1 counter on it. It gains haste until end of turn.

Llanowar Elves

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Boreal Druid

Thassa's Oracle

When Thassa's Oracle enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Hullbreaker Horror

Flash
This spell can't be countered.
Whenever you cast a spell, choose up to one —
• Return target spell you don't control to its owner's hand.
• Return target nonland permanent to its owner's hand.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Breaching Hippocamp

Flash (You may cast this spell any time you could cast an instant.)
When Breaching Hippocamp enters, untap another target creature you control.

Delighted Halfling

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a legendary spell, and that spell can't be countered.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Ghalta, Stampede Tyrant

Trample
When Ghalta, Stampede Tyrant enters, put any number of creature cards from your hand onto the battlefield.

Piper's Melody

Shuffle any number of target creature cards from your graveyard into your library.

Island

Chakram Retriever

Partner with Chakram Slinger (When this creature enters, target player may put Chakram Slinger into their hand from their library, then shuffle.)
Whenever you cast a spell during your turn, untap target creature.

Deadeye Navigator

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Deadeye Navigator is paired with another creature, each of those creatures has "{1}{U}: Exile this creature, then return it to the battlefield under your control."

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Wirewood Symbiote

Return an Elf you control to its owner's hand: Untap target creature. Activate only once each turn.

Hyrax Tower Scout

When Hyrax Tower Scout enters, untap target creature.

Dispel

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Haywire Mite

When Haywire Mite dies, you gain 2 life.
{G}, Sacrifice Haywire Mite: Exile target noncreature artifact or noncreature enchantment.