Marneus Calgar

Double strike
Master Tactician — Whenever one or more tokens you control enter, draw a card.
Chapter Master — {6}: Create two 2/2 white Astartes Warrior creature tokens with vigilance.

Captain Ripley Vance

Whenever you cast your third spell each turn, put a +1/+1 counter on Captain Ripley Vance, then it deals damage equal to its power to any target.

Ashling, Flame Dancer

You don't lose unspent red mana as steps and phases end.
Magecraft — Whenever you cast or copy an instant or sorcery spell, discard a card, then draw a card. If this is the second time this ability has resolved this turn, Ashling deals 2 damage to each opponent and each creature they control. If it's the third time, add {R}{R}{R}{R}.

Yenna, Redtooth Regent

{2}, {T}: Choose target enchantment you control that doesn't have the same name as another permanent you control. Create a token that's a copy of it, except it isn't legendary. If the token is an Aura, untap Yenna, then scry 2. Activate only as a sorcery.

Saint Traft and Rem Karolus

Whenever Saint Traft and Rem Karolus becomes tapped, create a 1/1 red Human creature token if this is the first time this ability has resolved this turn. If it's the second time, create a 1/1 blue Spirit creature token with flying. If it's the third time, create a 4/4 white Angel creature token with flying.
Whenever you cast a spell that has convoke, untap Saint Traft and Rem Karolus.

Euru, Acorn Scrounger

When Euru, Acorn Scrounger enters, you may forage. When you do, conjure a card named Chitterspitter onto the battlefield.
Whenever one or more Squirrels you control deal combat damage to a player, you may sacrifice a token. If you do, put an acorn counter on each permanent you control named Chitterspitter.

Jarsyl, Dark Age Scion

Starting intensity 1
At the beginning of combat on your turn, you may cast a spell with mana value equal to Jarsyl, Dark Age Scion's intensity from your graveyard without paying its mana cost. If you do, Jarsyl intensifies by 1.

Nadaar, Selfless Paladin

Vigilance
Whenever Nadaar enters or attacks, venture into the dungeon. (Enter the first room or advance to the next room.)
Other creatures you control get +1/+1 as long as you've completed a dungeon.

Zur the Enchanter

Flying
Whenever Zur attacks, you may search your library for an enchantment card with mana value 3 or less, put it onto the battlefield, then shuffle.

Hex, Kellan's Companion

Haste
Whenever you cast an Adventure spell, if Hex, Kellan's Companion is on the battlefield or in exile, it perpetually gets +1/+1. Then if it's on the battlefield, exile it with a fetch counter on it.
Whenever you cast a spell from exile, if Hex is in exile with a fetch counter on it, put it onto the battlefield.

Gyox, Brutal Carnivora

At the beginning of your end step, put an oil counter on up to one target creature.
Whenever a nontoken creature you control with one or more oil counters on it dies, conjure X duplicates of it into exile, where X is the number of oil counters on it. Those duplicates perpetually get +X/+X. Then shuffle those duplicates into your library.

Woah

Gutmorn, Pactbound Servant

Flying, deathtouch
When Gutmorn, Pactbound Servant enters the battlefield, each player discards a nonland card.
Whenever a player discards a card during your turn, they choose another player. That player conjures a duplicate of that card into their hand. It perpetually gains "You may spend mana as though it were mana of any color to cast this spell."

Narset, Jeskai Waymaster

At the beginning of your end step, you may discard your hand. If you do, draw cards equal to the number of spells you've cast this turn.

Stella Lee, Wild Card

Whenever you cast your second spell each turn, exile the top card of your library. Until the end of your next turn, you may play that card.
{T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy. Activate only if you've cast three or more spells this turn.

Alisaie Leveilleur

Partner with Alphinaud Leveilleur (When this creature enters, target player may put Alphinaud Leveilleur into their hand from their library, then shuffle.)
First strike
Dualcast — The second spell you cast each turn costs {2} less to cast.

Skullbriar, the Walking Grave

Haste
Whenever Skullbriar deals combat damage to a player, put a +1/+1 counter on it.
Counters remain on Skullbriar as it moves to any zone other than a player's hand or library.

Wild Goose Chase

Draw two cards, then discard two cards. Create a Food token.

Albiorix, Goose Tyrant

Flying, Trample, Ward {1}
Whenever you sacrifice a token, Albiorix perpetually gets +1/+1. This ability also triggers if Albiorix is in exile.

Albiorix, Goose Tyrant // Wild Goose Chase

Nira, Hellkite Duelist

Flash
Flying, trample, haste
When Nira, Hellkite Duelist enters, the next time you would lose the game this turn, instead draw three cards and your life total becomes 5.

Arek, False Goldwarden

Starting intensity 0
Whenever another creature enters under your control, cards you own named Arek, False Goldwarden intensify by 1.
{3}{W}{B}, {T}, Sacrifice Arek, False Goldwarden: Target opponent loses X life and you gain X life, where X is Arek's intensity.

Ertha Jo, Frontier Mentor

When Ertha Jo 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 you activate an ability that targets a creature or player, copy that ability. You may choose new targets for the copy.

Kellan, the Kid

Flying, lifelink
Whenever you cast a spell from anywhere other than your hand, you may cast a permanent spell with equal or lesser mana value from your hand without paying its mana cost. If you don't, you may put a land card from your hand onto the battlefield.

Lukamina, Moon Druid

Wild Shape — Specialize {3}. Activate only if you control six or more lands.
When Lukamina, Moon Druid enters, if you cast it, seek a land card with a basic land type.

Alphinaud Leveilleur

Partner with Alisaie Leveilleur (When this creature enters, target player may put Alisaie Leveilleur into their hand from their library, then shuffle.)
Vigilance
Eukrasia — Whenever you cast your second spell each turn, draw a card.

Darigaaz, Shivan Champion

Flying
At the beginning of your end step, conjure a random card from Darigaaz, Shivan Champion's spellbook into exile face down with three egg counters on it. It gains "At the beginning of your upkeep, if this card is exiled, remove an egg counter from it. Then if it has no egg counters on it, put it onto the battlefield."

Indris, the Hydrostatic Surge

When Indris, the Hydrostatic Surge enters, conjure a card named Lightning Bolt into your library. It perpetually gains storm. Then shuffle.
Whenever you cast an instant or sorcery spell, draw a card.

River Song

Meet in Reverse — You draw cards from the bottom of your library rather than the top.
Spoilers — Whenever an opponent scries, surveils, or searches their library, put a +1/+1 counter on River Song. Then River Song deals damage to that player equal to its power.

Breeches, the Blastmaker

Menace
Whenever you cast your second spell each turn, you may sacrifice an artifact. If you do, flip a coin. When you win the flip, copy that spell. You may choose new targets for the copy. When you lose the flip, Breeches deals damage equal to that spell's mana value to any target.

Buxton, Decorated Host

Convoke
At the beginning of your end step, if you control a tapped creature, seek a nonland permanent card with mana value X or less, where X is the number of tapped creatures you control. Put that card onto the battlefield.

Rusko, Clockmaker

When Rusko, Clockmaker enters the battlefield, conjure a card named Midnight Clock onto the battlefield.
Whenever you cast a noncreature spell, put an hour counter on each permanent you control named Midnight Clock. Each opponent loses 1 life and you gain 1 life.

Furgul, Quag Nurturer

At the beginning of your end step, conjure a card named Slimy Dualleech onto the battlefield if you control no Leeches. Otherwise, put a +1/+1 counter on each Leech you control.
{T}, Sacrifice a creature: Add an amount of {G} equal to the sacrificed creature's power.