Ancient Gold Dragon

Flying
Whenever Ancient Gold Dragon deals combat damage to a player, roll a d20. You create a number of 1/1 blue Faerie Dragon creature tokens with flying equal to the result.

Mentor of the Meek

Whenever another creature with power 2 or less enters the battlefield under your control, you may pay {1}. If you do, draw a card.

Lolth, Spider Queen

Whenever a creature you control dies, put a loyalty counter on Lolth, Spider Queen.
0: You draw a card and you lose 1 life.
−3: Create two 2/1 black Spider creature tokens with menace and reach.
−8: You get an emblem with "Whenever an opponent is dealt combat damage by one or more creatures you control, if that player lost less than 8 life this turn, they lose life equal to the difference."

Suture Priest

Whenever another creature enters the battlefield under your control, you may gain 1 life.
Whenever a creature enters the battlefield under an opponent's control, you may have that player lose 1 life.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Farmer Cotton

When Farmer Cotton enters the battlefield, create X 1/1 white Halfling creature tokens and X Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Merry, Warden of Isengard

Partner with Pippin, Warden of Isengard (When this creature enters the battlefield, target player may put Pippin into their hand from their library, then shuffle.)
Whenever one or more artifacts enter the battlefield under your control, create a 1/1 white Soldier creature token with lifelink. This ability triggers only once each turn.

Mondrak, Glory Dominus

If one or more tokens would be created under your control, twice that many of those tokens are created instead.
{1}{W/P}{W/P}, Sacrifice two other artifacts and/or creatures: Put an indestructible counter on Mondrak, Glory Dominus. ({W/P} can be paid with either {W} or 2 life.)

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Craterhoof Behemoth

Haste
When Craterhoof Behemoth enters the battlefield, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.

Sol Ring

Pippin, Warden of Isengard

Partner with Merry, Warden of Isengard (When this creature enters the battlefield, target player may put Merry into their hand from their library, then shuffle.)
{1}, {T}: Create a Food token.
{T}, Sacrifice four Foods: Other creatures you control get +3/+3 and gain haste until end of turn. Activate only as a sorcery.

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Chatterfang, Squirrel General

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
If one or more tokens would be created under your control, those tokens plus that many 1/1 green Squirrel creature tokens are created instead.
{B}, Sacrifice X Squirrels: Target creature gets +X/-X until end of turn.

Beledros Witherbloom

Flying
At the beginning of each upkeep, create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life."
Pay 10 life: Untap all lands you control. Activate only once each turn.

Elesh Norn, Mother of Machines

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

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Thalisse, Reverent Medium

At the beginning of each end step, create X 1/1 white Spirit creature tokens with flying, where X is the number of tokens you created this turn.

Drumbellower

Flying
Untap all creatures you control during each other player's untap step.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)