Ulasht, the Hate Seed

Ulasht enters with a +1/+1 counter on it for each other red creature you control and a +1/+1 counter on it for each other green creature you control.
{1}, Remove a +1/+1 counter from Ulasht: Choose one —
• Ulasht deals 1 damage to target creature.
• Create a 1/1 green Saproling creature token.

Tempting Wurm

When this creature enters, each opponent may put any number of artifact, creature, enchantment, and/or land cards from their hand onto the battlefield.

Palani's Hatcher

Other Dinosaurs you control have haste.
When this creature enters, create two 0/1 green Dinosaur Egg creature tokens.
At the beginning of combat on your turn, if you control one or more Eggs, sacrifice an Egg, then create a 3/3 green Dinosaur creature token.

Twinflame

Strive — This spell costs {2}{R} more to cast for each target beyond the first.
Choose any number of target creatures you control. For each of them, create a token that's a copy of that creature, except it has haste. Exile those tokens at the beginning of the next end step.

Tawnos's Coffin

You may choose not to untap this artifact during your untap step.
{3}, {T}: Exile target creature and all Auras attached to it. Note the number and kind of counters that were on that creature. When this artifact leaves the battlefield or becomes untapped, return that exiled card to the battlefield under its owner's control tapped with the noted number and kind of counters on it. If you do, return the other exiled cards to the battlefield under their owner's control attached to that permanent.

Worldgorger Dragon

Flying, trample
When this creature enters, exile all other permanents you control.
When this creature leaves the battlefield, return the exiled cards to the battlefield under their owners' control.

Roxanne, Starfall Savant

Whenever Roxanne enters or attacks, create a tapped colorless artifact token named Meteorite with "When this token enters, it deals 2 damage to any target" and "{T}: Add one mana of any color."
Whenever you tap an artifact token for mana, add one mana of any type that artifact token produced.

Stimulus Package

When this enchantment enters, create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")
Sacrifice a Treasure: Create a 1/1 green and white Citizen creature token.

Heat Shimmer

Create a token that's a copy of target creature, except it has haste and "At the beginning of the end step, exile this token."

Molten Duplication

Create a token that's a copy of target artifact or creature you control, except it's an artifact in addition to its other types. It gains haste until end of turn. Sacrifice it at the beginning of the next end step.

Orthion, Hero of Lavabrink

{1}{R}, {T}: Create a token that's a copy of another target creature you control. It gains haste. Sacrifice it at the beginning of the next end step. Activate only as a sorcery.
{6}{R}{R}{R}, {T}: Create five tokens that are copies of another target creature you control. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.

Ravager Wurm

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
When this creature enters, choose up to one —
• This creature fights target creature you don't control.
• Destroy target land with an activated ability that isn't a mana ability.

Bane of Progress

When this creature enters, destroy all artifacts and enchantments. Put a +1/+1 counter on this creature for each permanent destroyed this way.

Pyrewood Gearhulk

Vigilance, menace
When this creature enters, other creatures you control get +2/+2 and gain vigilance and menace until end of turn. Damage can't be prevented this turn.

Arbalest Engineers

When this creature enters, choose one —
• This creature deals 1 damage to any target.
• Put a +1/+1 counter on target creature. It gains trample and haste until end of turn.
• Create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Rionya, Fire Dancer

At the beginning of combat on your turn, create X tokens that are copies of another target creature you control, where X is one plus the number of instant and sorcery spells you've cast this turn. They gain haste. Exile them at the beginning of the next end step.

Slippery Bogbonder

Flash
Hexproof
When this creature enters, put a hexproof counter on target creature. Then move any number of counters from among creatures you control onto that creature.

Dragonlord Atarka

Flying, trample
When Dragonlord Atarka enters, it deals 5 damage divided as you choose among any number of target creatures and/or planeswalkers your opponents control.

Endurance

Flash
Reach
When this creature enters, up to one target player puts all the cards from their graveyard on the bottom of their library in a random order.
Evoke—Exile a green card from your hand.

Vithian Renegades

When this creature enters, destroy target artifact.

Burning-Tree Emissary

Migloz, Maze Crusher

Migloz enters with five oil counters on it.
{1}, Remove an oil counter from Migloz: It gains vigilance and menace until end of turn.
{2}, Remove two oil counters from Migloz: It gets +2/+2 until end of turn.
{3}, Remove three oil counters from Migloz: Destroy target artifact or enchantment.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.

Devastating Onslaught

Create X tokens that are copies of target artifact or creature you control. Those tokens gain haste until end of turn. Sacrifice them at the beginning of the next end step.

Dragonlord's Servant

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

Biotech Specialist

When this creature enters, create a Lander token. (It's an artifact with "{2}, {T}, Sacrifice this token: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.")
Whenever you sacrifice an artifact, this creature deals 2 damage to target opponent.

Godtracker of Jund

Whenever a creature you control with power 5 or greater enters, you may put a +1/+1 counter on this creature.

Panharmonicon

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

Jadecraft Artisan

When this creature enters, target creature gets +2/+2 until end of turn.

Avatar of Growth

This spell costs {1} less to cast for each opponent you have.
Trample
When this creature enters, each player searches their library for up to two basic land cards, puts them onto the battlefield, then shuffles.

Red XIII, Proud Warrior

Vigilance, trample
Other modified creatures you control have vigilance and trample. (Equipment, Auras you control, and counters are modifications.)
Cosmo Memory — When Red XIII enters, return target Aura or Equipment card from your graveyard to your hand.

Voyager Staff

{2}, Sacrifice this artifact: Exile target creature. Return the exiled card to the battlefield under its owner's control at the beginning of the next end step.

Electroduplicate

Create a token that's a copy of target creature you control, except it has haste and "At the beginning of the end step, sacrifice this token."
Flashback {2}{R}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)