Nesting Dovehawk

Flying
At the beginning of combat on your turn, populate. (Create a token that's a copy of a creature token you control.)
Whenever a creature token you control enters, put a +1/+1 counter on Nesting Dovehawk.

Cleric of the Forward Order

When Cleric of the Forward Order enters, you gain 2 life for each creature you control named Cleric of the Forward Order.

sussy

Ruby Medallion

Red spells you cast cost {1} less to cast.

Powder Ganger

Squad {2} (As an additional cost to cast this spell, you may pay {2} any number of times. When this creature enters, create that many tokens that are copies of it.)
When Powder Ganger enters, destroy up to one target artifact.

Sol Ring

Securitron Squadron

Squad {3} (As an additional cost to cast this spell, you may pay {3} any number of times. When this creature enters, create that many tokens that are copies of it.)
Vigilance
Whenever a creature token you control enters, put a +1/+1 counter on it.

Loyal Warhound

Vigilance
When Loyal Warhound enters, if an opponent controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.

Endless Evil

Enchant creature you control
At the beginning of your upkeep, create a token that's a copy of enchanted creature, except the token is 1/1.
When enchanted creature dies, if that creature was a Horror, return Endless Evil to its owner's hand.

White Orchid Phantom

Flying, first strike
When White Orchid Phantom enters, destroy up to one target nonbasic land. Its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.

Hedron Archive

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

Muster the Departed

When Muster the Departed enters, create a 1/1 white Spirit creature token with flying.
Morbid — At the beginning of your end step, if a creature died this turn, populate. (Create a token that's a copy of a creature token you control.)

Worn Powerstone

Worn Powerstone enters tapped.
{T}: Add {C}{C}.

Augury Owl

Flying
When Augury Owl enters, scry 3. (Look at the top three cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Thundertrap Trainer

Offspring {4} (You may pay an additional {4} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
When this creature enters, 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.

Charismatic Conqueror

Vigilance
Whenever an artifact or creature an opponent controls enters untapped, they may tap that permanent. If they don't, you create a 1/1 white Vampire creature token with lifelink.

Horned Stoneseeker

Menace
When Horned Stoneseeker enters, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")
When Horned Stoneseeker leaves the battlefield, sacrifice a Powerstone.

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.)

Cayth, Famed Mechanist

Fabricate 1 (When this creature enters, put a +1/+1 counter on it or create a 1/1 colorless Servo artifact creature token.)
Other nontoken creatures you control have fabricate 1.
{2}, {T}: Choose one —
• Populate.
• Proliferate.

Phyrexian Revoker

As Phyrexian Revoker enters, choose a nonland card name.
Activated abilities of sources with the chosen name can't be activated.

Dockside Extortionist

When Dockside Extortionist enters, create X Treasure tokens, where X is the number of artifacts and enchantments your opponents control. (Treasure tokens are artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Gary Clone

Squad {2} (As an additional cost to cast this spell, you may pay {2} any number of times. When this creature enters, create that many tokens that are copies of it.)
Whenever Gary Clone attacks, each creature you control named Gary Clone gets +1/+0 until end of turn.

Ghastly Mimicry

Enchant creature
At the beginning of your upkeep, create a token that's a copy of enchanted creature, except it's a Spirit in addition to its other types.
If Ghastly Mimicry would be put into a graveyard from anywhere, exile it instead.

Mirrorhall Mimic

You may have Mirrorhall Mimic enter as a copy of any creature on the battlefield, except it's a Spirit in addition to its other types.
Disturb {3}{U}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Mirrorhall Mimic // Ghastly Mimicry

Sicarian Infiltrator

Flash
Squad {2} (As an additional cost to cast this spell, you may pay {2} any number of times. When this creature enters, create that many tokens that are copies of it.)
Benediction of the Omnissiah — When Sicarian Infiltrator enters, draw a card.

Ultramarines Honour Guard

Squad {2} (As an additional cost to cast this spell, you may pay {2} any number of times. When this creature enters, create that many tokens that are copies of it.)
Other creatures you control get +1/+1.

Thrill-Kill Disciple

Squad—{1}, Discard a card. (As an additional cost to cast this spell, you may pay its squad cost any number of times. When this creature enters, create that many tokens that are copies of it.)
When Thrill-Kill Disciple dies, create a Junk token.

Volatile Stormdrake

Flying, hexproof from activated and triggered abilities
When Volatile Stormdrake enters, exchange control of Volatile Stormdrake and target creature an opponent controls. If you do, you get {E}{E}{E}{E}, then sacrifice that creature unless you pay an amount of {E} equal to its mana value.

Panharmonicon

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

Cloud of Faeries

Flying
When Cloud of Faeries enters, untap up to two lands.
Cycling {2} ({2}, Discard this card: Draw a card.)

Agate Instigator

Offspring {1}{R} (You may pay an additional {1}{R} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever another creature you control enters, this creature deals 1 damage to each opponent.

Knight of the White Orchid

First strike
When Knight of the White Orchid enters, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield, then shuffle.

Vanguard Suppressor

Squad {2} (As an additional cost to cast this spell, you may pay {2} any number of times. When this creature enters, create that many tokens that are copies of it.)
Flying
Suppressing Fire — Whenever Vanguard Suppressor deals combat damage to a player, draw a card.

Pearl Medallion

White spells you cast cost {1} less to cast.

Tax Collector

When Tax Collector enters, choose one —
• Tax — Until your next turn, spells your opponents cast cost {1} more to cast.
• Arrest — Detain target creature an opponent controls. (Until your next turn, that creature can't attack or block and its activated abilities can't be activated.)

Zinnia, Valley's Voice

Flying
Zinnia, Valley's Voice gets +X/+0, where X is the number of other creatures you control with base power 1.
Creature spells you cast have offspring {2}. (You may pay an additional {2} as you cast a creature spell. If you do, when that creature enters, create a 1/1 token copy of it.)

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Space Marine Devastator

Squad {2} (As an additional cost to cast this spell, you may pay {2} any number of times. When this creature enters, create that many tokens that are copies of it.)
Grav-cannon — When Space Marine Devastator enters, destroy up to one target artifact or enchantment.