Deadwood Treefolk

Vanishing 3 (This creature enters the battlefield with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Deadwood Treefolk enters or leaves the battlefield, return another target creature card from your graveyard to your hand.

Atraxa, Grand Unifier

Flying, vigilance, deathtouch, lifelink
When Atraxa, Grand Unifier enters the battlefield, reveal the top ten cards of your library. For each card type, you may put a card of that type from among the revealed cards into your hand. Put the rest on the bottom of your library in a random order. (Artifact, battle, creature, enchantment, instant, land, planeswalker, and sorcery are card types.)

Aven Riftwatcher

Flying
Vanishing 3 (This creature enters the battlefield with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Aven Riftwatcher enters or leaves the battlefield, you gain 2 life.

Vishgraz, the Doomhive

Menace, toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
When Vishgraz, the Doomhive enters the battlefield, create three 1/1 colorless Phyrexian Mite artifact creature tokens with toxic 1 and "This creature can't block."
Vishgraz gets +1/+1 for each poison counter your opponents have.

Candlekeep Sage

Commander creatures you own have "When this creature enters or leaves the battlefield, draw a card."

Night Incarnate

Deathtouch
When Night Incarnate leaves the battlefield, all creatures get -3/-3 until end of turn.
Evoke {3}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

Astral Dragon

Flying
Project Image — When Astral Dragon enters the battlefield, create two tokens that are copies of target noncreature permanent, except they're 3/3 Dragon creatures in addition to their other types, and they have flying.

Torsten, Founder of Benalia

When Torsten, Founder of Benalia enters the battlefield, reveal the top seven cards of your library. Put any number of creature and/or land cards from among them into your hand and the rest on the bottom of your library in a random order.
When Torsten dies, create seven 1/1 white Soldier creature tokens.

Chittering Witch

When Chittering Witch enters the battlefield, create a number of 1/1 black Rat creature tokens equal to the number of opponents you have.
{1}{B}, Sacrifice a creature: Target creature gets -2/-2 until end of turn.

Company Commander

Command Section — When Company Commander enters the battlefield, create a number of 1/1 white Soldier creature tokens equal to the number of opponents you have.
Bring it Down! — Whenever Company Commander attacks, creatures you control gain deathtouch until end of turn.

Clockwork Fox

When Clockwork Fox leaves the battlefield, you draw two cards and each opponent draws a card.

Myr Battlesphere

When Myr Battlesphere enters the battlefield, create four 1/1 colorless Myr artifact creature tokens.
Whenever Myr Battlesphere attacks, you may tap X untapped Myr you control. If you do, Myr Battlesphere gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Toothy, Imaginary Friend

Partner with Pir, Imaginative Rascal (When this creature enters the battlefield, target player may put Pir into their hand from their library, then shuffle.)
Whenever you draw a card, put a +1/+1 counter on Toothy, Imaginary Friend.
When Toothy leaves the battlefield, draw a card for each +1/+1 counter on it.

Somberwald Beastmaster

When Somberwald Beastmaster enters the battlefield, create a 2/2 green Wolf creature token, a 3/3 green Beast creature token, and a 4/4 green Beast creature token.
Creature tokens you control have deathtouch.

Reality Acid

Enchant permanent
Vanishing 3 (This Aura enters the battlefield with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Reality Acid leaves the battlefield, enchanted permanent's controller sacrifices it.

Thragtusk

When Thragtusk enters the battlefield, you gain 5 life.
When Thragtusk leaves the battlefield, create a 3/3 green Beast creature token.