Don't Have

Aether Charge

Whenever a Beast you control enters, you may have it deal 4 damage to target opponent or planeswalker.

Getting

Chainsaw

When this Equipment enters, it deals 3 damage to up to one target creature.
Whenever one or more creatures die, put a rev counter on this Equipment.
Equipped creature gets +X/+0, where X is the number of rev counters on this Equipment.
Equip {3}

Melded Moxite

When this artifact enters, you may discard a card. If you do, draw two cards.
{3}, Sacrifice this artifact: Create a tapped 2/2 colorless Robot artifact creature token.

Lathliss, Dragon Queen

Flying
Whenever another nontoken Dragon you control enters, create a 5/5 red Dragon creature token with flying.
{1}{R}: Dragons you control get +1/+0 until end of turn.

Outpost Siege

As this enchantment enters, choose Khans or Dragons.
• Khans — At the beginning of your upkeep, exile the top card of your library. Until end of turn, you may play that card.
• Dragons — Whenever a creature you control leaves the battlefield, this enchantment deals 1 damage to any target.

Molten Gatekeeper

Whenever another creature you control enters, this creature deals 1 damage to each opponent.
Unearth {R} ({R}: 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.)

Molten Primordial

Haste
When this creature enters, for each opponent, gain control of up to one target creature that player controls until end of turn. Untap those creatures. They gain haste until end of turn.

Thunder Dragon

Flying
When this creature enters, it deals 3 damage to each creature without flying.

Knollspine Dragon

Flying
When this creature enters, you may discard your hand and draw cards equal to the damage dealt to target opponent this turn.

Caldera Hellion

Devour 1 (As this creature enters, you may sacrifice any number of creatures. It enters with that many +1/+1 counters on it.)
When this creature enters, it deals 3 damage to each creature.

Bogardan Hellkite

Flash
Flying
When this creature enters, it deals 5 damage divided as you choose among any number of targets.

Have

Red Dragon

Flying
Fire Breath — When this creature enters, it deals 4 damage to each opponent.

Dong Zhou, the Tyrant

When Dong Zhou enters, target creature an opponent controls deals damage equal to its power to that player.

Wedding Invitation

When this artifact enters, draw a card.
{T}, Sacrifice this artifact: Target creature can't be blocked this turn. If it's a Vampire, it also gains lifelink until end of turn.

Outrage Shaman

Chroma — When this creature enters, it deals damage to target creature equal to the number of red mana symbols in the mana costs of permanents you control.

Zealous Conscripts

Haste
When this creature enters, gain control of target permanent until end of turn. Untap that permanent. It gains haste until end of turn.

Behemoth of Vault 0

Trample
When this creature enters, you get {E}{E}{E}{E} (four energy counters).
When this creature dies, you may pay an amount of {E} equal to target nonland permanent's mana value. When you do, destroy that permanent.

Aligned Hedron Network

When this artifact enters, exile all creatures with power 5 or greater until this artifact leaves the battlefield. (Those creatures return under their owners' control.)

Koth, Fire of Resistance

+2: Search your library for a basic Mountain card, reveal it, put it into your hand, then shuffle.
−3: Koth deals damage to target creature equal to the number of Mountains you control.
−7: You get an emblem with "Whenever a Mountain you control enters, this emblem deals 4 damage to any target."

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.

Vexing Devil

When this creature enters, any opponent may have it deal 4 damage to them. If a player does, sacrifice this creature.

Where Ancients Tread

Whenever a creature you control with power 5 or greater enters, you may have this enchantment deal 5 damage to any target.

Dauntless Scrapbot

When this creature enters, exile each opponent's graveyard. 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.")

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 this creature enters, destroy up to one target artifact.

Conquering Manticore

Flying
When this creature enters, gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn.

Storm Caller

When this creature enters, it deals 2 damage to each opponent.

Sarkhan, Dragon Ascendant

When Sarkhan enters, you may behold a Dragon. If you do, create a Treasure token. (To behold a Dragon, choose a Dragon you control or reveal a Dragon card from your hand.)
Whenever a Dragon you control enters, put a +1/+1 counter on Sarkhan. Until end of turn, Sarkhan becomes a Dragon in addition to its other types and gains flying.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Dualcaster Mage

Flash
When this creature enters, copy target instant or sorcery spell. You may choose new targets for the copy.

Moraug, Fury of Akoum

Each creature you control gets +1/+0 for each time it has attacked this turn.
Landfall — Whenever a land you control enters, if it's your main phase, there's an additional combat phase after this phase. At the beginning of that combat, untap all creatures you control.

Bogardan Rager

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, target creature gets +4/+0 until end of turn.

Territory Forge

When this artifact enters, if you cast it, exile target artifact or land.
This artifact has all activated abilities of the exiled card.

Pandemonium

Whenever a creature enters, that creature's controller may have it deal damage equal to its power to any target of their choice.