Watcher for Tomorrow

Hideaway 4 (When this creature enters the battlefield, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
Watcher for Tomorrow enters the battlefield tapped.
When Watcher for Tomorrow leaves the battlefield, put the exiled card into its owner's hand.

Sanctifier en-Vec

Protection from black and from red
When Sanctifier en-Vec enters the battlefield, exile all cards that are black or red from all graveyards.
If a black or red permanent, spell, or card not on the battlefield would be put into a graveyard, exile it instead.

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Unsettled Mariner

Changeling (This card is every creature type.)
Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Reflector Mage

When Reflector Mage enters the battlefield, return target creature an opponent controls to its owner's hand. That creature's owner can't cast spells with the same name as that creature until your next turn.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Noble Hierarch

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {G}, {W}, or {U}.

Thalia, Guardian of Thraben

First strike
Noncreature spells cost {1} more to cast.

Meddling Mage

As Meddling Mage enters the battlefield, choose a nonland card name.
Spells with the chosen name can't be cast.

Soul Warden

Whenever another creature enters the battlefield, you gain 1 life.

Misty Rainforest

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Cathar Commando

Flash
{1}, Sacrifice Cathar Commando: Destroy target artifact or enchantment.

Prismatic Ending

Converge — Exile target nonland permanent if its mana value is less than or equal to the number of colors of mana spent to cast this spell.

Windswept Heath

{T}, Pay 1 life, Sacrifice Windswept Heath: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

Venser, Shaper Savant

Flash
When Venser, Shaper Savant enters the battlefield, return target spell or permanent to its owner's hand.

Temple Garden

({T}: Add {G} or {W}.)
As Temple Garden enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Sanctum Prelate

As Sanctum Prelate enters the battlefield, choose a number.
Noncreature spells with mana value equal to the chosen number can't be cast.

Champion of the Parish

Whenever another Human enters the battlefield under your control, put a +1/+1 counter on Champion of the Parish.

Island

Augur of Autumn

You may look at the top card of your library any time.
You may play lands from the top of your library.
Coven — As long as you control three or more creatures with different powers, you may cast creature spells from the top of your library.

Breeding Pool

({T}: Add {G} or {U}.)
As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Collected Company

Look at the top six cards of your library. Put up to two creature cards with mana value 3 or less from among them onto the battlefield. Put the rest on the bottom of your library in any order.

Plains

Moonrage Brute

First strike
Ward—Pay 3 life.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Brutal Cathar

When this creature enters the battlefield or transforms into Brutal Cathar, exile target creature an opponent controls until this creature leaves the battlefield.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Brutal Cathar // Moonrage Brute

Thalia's Lieutenant

When Thalia's Lieutenant enters the battlefield, put a +1/+1 counter on each other Human you control.
Whenever another Human enters the battlefield under your control, put a +1/+1 counter on Thalia's Lieutenant.