Witty Roastmaster

Alliance — Whenever another creature you control enters, Witty Roastmaster deals 1 damage to each opponent.

Gala Greeters

Alliance — Whenever another creature you control enters, choose one that hasn't been chosen this turn —
• Put a +1/+1 counter on Gala Greeters.
• Create a tapped Treasure token.
• You gain 2 life.

Playable Delusionary Hydra

{TK}{TK} — {T}: Draw a card, then discard a card.
{TK}{TK}{TK}{TK} — Whenever this creature attacks, you gain 3 life and draw a card.
{TK}{TK} — 1/5
{TK}{TK}{TK} — 4/4

Chord of Calling

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.)
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Rocco, Cabaretti Caterer

When Rocco, Cabaretti Caterer enters, if you cast it, you may search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Arbaaz Mir

Whenever Arbaaz Mir or another nontoken historic permanent you control enters, Arbaaz Mir deals 1 damage to each opponent and you gain 1 life. (Artifacts, legendaries, and Sagas are historic.)

Enduring Innocence

Lifelink
Whenever one or more other creatures you control with power 2 or less enter, draw a card. This ability triggers only once each turn.
When Enduring Innocence dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Cool Fluffy Loxodon

{TK}{TK} — When this permanent leaves the battlefield, draw a card.
{TK}{TK}{TK}{TK}{TK} — Whenever a creature enters under your control, this permanent becomes a 13/13 Eldrazi creature in addition to its other types until end of turn.
{TK}{TK} — 4/2
{TK}{TK}{TK}{TK} — 5/6

Geek Lotus Warrior

{TK}{TK} — {2}: This creature gets +2/+0 until end of turn.
{TK}{TK}{TK}{TK} — Whenever a creature enters under your control, this permanent deals 2 damage to target player.
{TK}{TK} — 4/1
{TK}{TK}{TK} — 3/6

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Panharmonicon

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

Giant Mana Cake

{TK}{TK} — When this permanent leaves the battlefield, create two Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
{TK}{TK}{TK}{TK} — When this permanent dies, destroy target nonland permanent.
{TK}{TK} — 3/3
{TK}{TK}{TK} — 6/2

Command Beacon

{T}: Add {C}.
{T}, Sacrifice Command Beacon: Put your commander into your hand from the command zone.

Warleader's Call

Creatures you control get +1/+1.
Whenever a creature you control enters, Warleader's Call deals 1 damage to each opponent.

Deep-Fried Plague Myr

{TK}{TK} — Whenever this creature attacks, scry 1.
{TK}{TK}{TK} — Whenever this permanent leaves the battlefield, you may destroy target artifact or enchantment.
{TK}{TK}{TK} — 4/5
{TK}{TK}{TK}{TK} — 8/4

Trained Blessed Mind

{TK}{TK} — {T}: Exile target card from a graveyard.
{TK}{TK}{TK} — Threshold — As long as seven or more cards are in your graveyard, this creature gets +4/+0 and has trample.
{TK}{TK} — 4/2
{TK}{TK}{TK}{TK}{TK} — 6/9

Archdruid's Charm

Choose one —
• Search your library for a creature or land card and reveal it. Put it onto the battlefield tapped if it's a land card. Otherwise, put it into your hand. Then shuffle.
• Put a +1/+1 counter on target creature you control. It deals damage equal to its power to target creature you don't control.
• Exile target artifact or enchantment.

Welcoming Vampire

Flying
Whenever one or more other creatures you control with power 2 or less enter, draw a card. This ability triggers only once each turn.

Finale of Devastation

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.

Wirewood Symbiote

Return an Elf you control to its owner's hand: Untap target creature. Activate only once each turn.

Goblin Coward Parade

{TK}{TK} — Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
{TK}{TK}{TK} — When this permanent leaves the battlefield, you may destroy target creature with power 4 or greater.
{TK}{TK} — 2/3
{TK}{TK}{TK}{TK} — 8/4

Sassy Gremlin Blood

{TK}{TK} — Whenever this creature attacks, create a Treasure token.
{TK}{TK}{TK}{TK}{TK} — {3}: Target creature gains flying until end of turn.
{TK}{TK} — 3/2
{TK}{TK}{TK}{TK}{TK}{TK} — 10/10

Angelic Sell-Sword

Flying, vigilance
Whenever Angelic Sell-Sword or another nontoken creature you control enters, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."
Whenever Angelic Sell-Sword attacks, if its power is 6 or greater, draw a card.

Yawgmoth Merfolk Soul

{TK}{TK} — When this permanent leaves the battlefield, target player discards a card.
{TK}{TK}{TK}{TK}{TK} — When this permanent leaves the battlefield, create five 1/1 white Clown Robot artifact creature tokens.
{TK}{TK} — 3/3
{TK}{TK}{TK}{TK} — 6/5

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Gandalf the White

Flash
You may cast legendary spells and artifact spells as though they had flash.
If a legendary permanent or an artifact entering or leaving the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Phyrexian Midway Bamboozle

{TK}{TK} — Whenever this creature attacks, you get {TK}.
{TK}{TK}{TK} — Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)
{TK}{TK} — 4/2
{TK}{TK}{TK}{TK}{TK} — 6/9

Park Bleater

Whenever another creature you own enters, you get {TK}.
{W}, {T}: You may put a sticker on a creature you own that entered this turn.

Blessed Sanctuary

Prevent all noncombat damage that would be dealt to you and creatures you control.
Whenever a nontoken creature you control enters, create a 2/2 white Unicorn creature token.

Guardian Project

Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Riftsweeper

When Riftsweeper enters, choose target face-up exiled card. Its owner shuffles it into their library.

Karmic Guide

Flying, protection from black
Echo {3}{W}{W} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Karmic Guide enters, return target creature card from your graveyard to the battlefield.

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

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.

Aura Shards

Whenever a creature you control enters, you may destroy target artifact or enchantment.

Saltskitter

Whenever another creature enters, exile Saltskitter. Return Saltskitter to the battlefield under its owner's control at the beginning of the next end step.

Temur Sabertooth

{1}{G}: You may return another creature you control to its owner's hand. If you do, Temur Sabertooth gains indestructible until end of turn.

Norin the Wary

When a player casts a spell or a creature attacks, exile Norin the Wary. Return it to the battlefield under its owner's control at the beginning of the next end step.

Molten Gatekeeper

Whenever another creature you control enters, Molten Gatekeeper 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.)

Rumor Gatherer

Alliance — Whenever another creature you control enters, scry 1. If this is the second time this ability has resolved this turn, draw a card instead.

Elesh Norn, Mother of Machines

Vigilance
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Permanents entering don't cause abilities of permanents your opponents control to trigger.

Cloudstone Curio

Whenever a nonartifact permanent you control enters, you may return another permanent you control that shares a permanent type with it to its owner's hand.

Sanctum of Eternity

{T}: Add {C}.
{2}, {T}: Return target commander you own from the battlefield to your hand. Activate only during your turn.