Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Rootborn Defenses

Populate. Creatures you control gain indestructible until end of turn. (To populate, create a token that's a copy of a creature token you control.)

Benalish Marshal

Selfless Spirit

Flying
Sacrifice this creature: Creatures you control gain indestructible until end of turn.

Dauntless Bodyguard

As this creature enters, choose another creature you control.
Sacrifice this creature: The chosen creature gains indestructible until end of turn.

Mentor of the Meek

Whenever another creature you control with power 2 or less enters, you may pay {1}. If you do, draw a card.

Benevolent Bodyguard

Sacrifice this creature: Target creature you control gains protection from the color of your choice until end of turn.

Dust Elemental

Flash (You may cast this spell any time you could cast an instant.)
Flying; fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
When this creature enters, return three creatures you control to their owner's hand.

Odric, Lunarch Marshal

At the beginning of each combat, creatures you control gain first strike until end of turn if a creature you control has first strike. The same is true for flying, deathtouch, double strike, haste, hexproof, indestructible, lifelink, menace, reach, skulk, trample, and vigilance.

Ugin's Conjurant

This creature enters with X +1/+1 counters on it.
If damage would be dealt to this creature while it has a +1/+1 counter on it, prevent that damage and remove that many +1/+1 counters from this creature.

Reverent Mantra

You may exile a white card from your hand rather than pay this spell's mana cost.
Choose a color. All creatures gain protection from the chosen color until end of turn.

Imposing Sovereign

Creatures your opponents control enter tapped.

Binding Mummy

Whenever another Zombie you control enters, you may tap target artifact or creature.

Emancipation Angel

Flying
When this creature enters, return a permanent you control to its owner's hand.

Kami of False Hope

Sacrifice this creature: Prevent all combat damage that would be dealt this turn.

Scapegoat

As an additional cost to cast this spell, sacrifice a creature.
Return any number of target creatures you control to their owner's hand.

Loyal Sentry

When this creature blocks a creature, destroy that creature and this creature.

Marble Diamond

This artifact enters tapped.
{T}: Add {W}.

Oketra's Monument

White creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, create a 1/1 white Warrior creature token with vigilance.

Resolute Watchdog

Defender
{1}, Sacrifice this creature: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Leonin Relic-Warder

When this creature enters, you may exile target artifact or enchantment.
When this creature leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Soul Warden

Whenever another creature enters, you gain 1 life.

Victory's Herald

Flying
Whenever this creature attacks, attacking creatures gain flying and lifelink until end of turn.

War Priest of Thune

When this creature enters, you may destroy target enchantment.

Palladium Myr

Stormfront Riders

Flying
When this creature enters, return two creatures you control to their owner's hand.
Whenever this creature or another creature is returned to your hand from the battlefield, create a 1/1 white Soldier creature token.

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Draw two cards.

Blood Clock

At the beginning of each player's upkeep, that player returns a permanent they control to its owner's hand unless they pay 2 life.

Oblation

The owner of target nonland permanent shuffles it into their library, then draws two cards.

Stonecloaker

Flash
Flying
When this creature enters, return a creature you control to its owner's hand.
When this creature enters, exile target card from a graveyard.

Endless One

This creature enters with X +1/+1 counters on it.

Bygone Bishop

Flying
Whenever you cast a creature spell with mana value 3 or less, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Make a Stand

Creatures you control get +1/+0 and gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Plains

Thraben Inspector

When this creature enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Eiganjo Free-Riders

Flying
At the beginning of your upkeep, return a white creature you control to its owner's hand.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Whitemane Lion

Flash
When this creature enters, return a creature you control to its owner's hand.

Wall of Omens

Defender
When this creature enters, draw a card.

Manakin

Akroma's Blessing

Choose a color. Creatures you control gain protection from the chosen color until end of turn.
Cycling {W} ({W}, Discard this card: Draw a card.)

Gold Myr

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Ancestral Statue

When this creature enters, return a nonland permanent you control to its owner's hand.

Venerated Loxodon

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
When this creature enters, put a +1/+1 counter on each creature that convoked it.

Phyrexian Walker

Martyred Rusalka

{W}, Sacrifice a creature: Target creature can't attack this turn.

Shifting Wall

Defender (This creature can't attack.)
This creature enters with X +1/+1 counters on it.

God-Eternal Oketra

Double strike
Whenever you cast a creature spell, create a 4/4 black Zombie Warrior creature token with vigilance.
When God-Eternal Oketra dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Children of Korlis

Sacrifice this creature: You gain life equal to the life you've lost this turn. (Damage causes loss of life.)

Umbilicus

At the beginning of each player's upkeep, that player may pay 2 life. If they don't, they return a permanent they control to its owner's hand.

Infiltration Lens

Whenever equipped creature becomes blocked by a creature, you may draw two cards.
Equip {1}

Alms Collector

Flash
If an opponent would draw two or more cards, instead you and that player each draw a card.

Aviary Mechanic

When this creature enters, you may return another permanent you control to its owner's hand.

Angelic Chorus

Whenever a creature you control enters, you gain life equal to its toughness.

Ornithopter

Jeskai Barricade

Flash (You may cast this spell any time you could cast an instant.)
Defender
When this creature enters, you may return another target creature you control to its owner's hand.

Mardu Woe-Reaper

Whenever this creature or another Warrior you control enters, you may exile target creature card from a graveyard. If you do, you gain 1 life.

Subjugator Angel

Flying
When this creature enters, tap all creatures your opponents control.

Skyscanner

Flying
When this creature enters, draw a card.

Signal Pest

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
This creature can't be blocked except by creatures with flying or reach.

Hedron Crawler

{T}: Add {C}. ({C} represents colorless mana.)

Conclave Phalanx

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
When this creature enters, you gain 1 life for each creature you control.

Kor Skyfisher

Valor in Akros

Whenever a creature you control enters, creatures you control get +1/+1 until end of turn.