msem-instigator

Yi Cang, Thief of Blessings enters with a +1/+1 counter on them.
{1}: Yi Cang becomes a copy of target creature in their pack, except their name is Yi Cang, Thief of Blessings, they're legendary in addition to their other types, and they have this ability. (Two or more creatures you control with equal power are in a pack.)

Flying
When Dune Wraith enters, distribute two +1/+1 counters among Spirits you control.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Eager Hatchling has three or more +1/+1 counters on it, remove them all and transform it.

Whenever you make first contact, Entelan Idealist gets +2/+2 until end of turn. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

When Gamhaugen Stablehand enters, put a +1/+1 counter on target creature you control. You gain 1 life.

Flying
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

When Hinasa Lorekeeper enters, create a 2/2 colorless Spirit creature token.
Colorless creatures you control have vigilance.

At the beginning of each opponent's end step, that player gets a poison counter unless damage was dealt this turn.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Remove a +1/+1 counter from Kor Skyknight: It gains flying until end of turn.

Shimmer (Whenever this creature attacks, create a tapped and attacking token that's a copy of it. Exile the token at the beginning of the end step.)
Lha Elite's power is equal to the number of tokens you control.

When Overgrowth Guardian enters, germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

{T}, Tap an untapped creature you control: You gain 2 life.

Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)
Whenever Robot Herder deals combat damage to a player, create a 1/1 colorless Servo artifact creature token.

Schoolmaster gets +1/+1 for each other Merfolk you control.
When Schoolmaster enters, create a 1/1 white Merfolk creature token.

When Solar Wisp enters, put a +1/+1 counter on target creature.

When Teikoku Songcrafter enters, create a 2/2 colorless Spirit creature token.
Whenever a colorless creature you control enters, put a +1/+1 counter on it.

{3}{W}: Exile Vanishing Memory and target creature an opponent controls.

Whenever a creature you control dies, you may pay {W}. If you do, you get a glory counter. (You lose glory counters before life. A player with ten or more glory counters wins the game.)
{2}{W}, {T}: Return target creature card from your graveyard to the battlefield. Activate this ability only if you are glorious.

Knight spells you cast cost {1} less to cast.

Eureka! (At the beginning of each end step, you get a research counter if you cast a spell this turn. Then if you have eight or more research counters, remove them and create a Masterpiece token of your choice.)
{T}: Draw a card, then discard a card.

When Debt Dignitary enters, tap target nonland permanent. That permanent doesn't untap during its controller's untap step for as long as you control Debt Dignitary.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Determined Koi has three or more +1/+1 counters on it, remove them all and transform it.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Hinasa Mystic enters, draw a card.

{T}: Scry 1.
{1}{U}, {T}: Reveal the bottom card of your library. If it's an artifact or enchantment card, put it into your hand.

When Seishin Tidekeeper enters, create a 2/2 colorless Spirit creature token.
Colorless creatures you control have flying.