msem-instigator

Reach, trample
Improve {1}{B/G} ({1}{B/G}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever one or more +1/+1 counters are put on Gorganith, Ruin Maw, you may search your library and/or graveyard for a creature card with mana value equal to or less than the number of +1/+1 counters on Gorganith and put it onto the battlefield. If you search your library this way, shuffle.

Scry 2, then draw two cards. You lose 2 life.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This creature gets +2/+2 and has trample as long as it's merged with another card or token.

Create a 2/2 red and white Cat Knight creature token. Creatures you control get +1/+1 and gain haste until end of turn.

Flying
Whenever another artifact you control enters, Filigree Drake gets +1/+1 until end of turn.

Lifelink
At the beginning of each end step, if you gained life this turn, you may pay {W/B}. If you do, create a 1/1 white Spirit creature token with flying.

At the beginning of your upkeep, each player conjures a card named Data-Point into their hand. (It's a sorcery that costs {2} with “Draw a card.”)

Unveil {3}{G}{W} ({3}{G}{W}: Transform this. Unveil only as a sorcery.)

At the beginning of your upkeep, if the number of permanents you control, the number of cards in your hand, and the number of cards in your graveyard are all equal, you win the game.

As Rhythm of Kaneh enters, choose Andazir or Mahara.
• Andazir — Whenever a creature you control attacks, defending player discards a card.
• Mahara — Whenever a nontoken creature you control dies, amass Soldiers X, where X is that creature's power.

At the beginning of each end step, if a player lost 5 or more life this turn, create a 5/5 black Demon creature token with flying.

Trample
Other Bears you control get +2/+2.

You may cast this spell without paying its mana cost if it's the only card in your hand.
Counter target spell.

When Dread Elk dies, put a +1/+1 counter on target creature you control. If that creature is a Zombie, put two +1/+1 counters on it instead.
Foreshadow {5}{B} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

Flying
{R}: Volatile Elemental gets +1/+0 until end of turn.

Create three 1/1 white Peasant creature tokens. Scry 1.

Menace
When Doomed Questant enters, each opponent sacrifices a creature and discards a card.

This spell costs {2} less to cast if you've cast both an instant spell and a sorcery spell this turn.
Haste

Trample
When Bank Skimmer enters, create a green Aura enchantment token named Turtle's Valor attached to target creature. The token has enchant creature and “Enchanted creature gets +X/+X, where X is its mana value.”

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever Loyal Firestarter attacks, you may cast an instant or sorcery spell from your hand with mana value less than or equal to Loyal Firestarter's power without paying its mana cost.

Trial 2 (As you cast this spell, an opponent of your choice may pay 2 life. If they don't, they fail the trial.)
When Nascent Adversary enters, if the trial was failed, it gains haste and first strike until end of turn.

When Minister of Madness enters, create a 0/1 blue Weird creature token with flying.
{2}{U}, Sacrifice a creature: Search your library for an instant or sorcery card with mana value equal to 1 plus the sacrificed creature's mana value, exile that card, then shuffle. Then you may cast that card without paying its mana cost. Activate only as a sorcery.

Hub of Innovation enters tapped.
At the beginning of your upkeep, if you control five or more artifacts, draw a card.
{T}: Add {C}.

At the beginning of each end step, if a creature an opponent controlled died this turn, return a creature card from your graveyard to the battlefield.

When Seafloor Wreckage enters and when you sacrifice it, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
{1}{G}, Sacrifice Seafloor Wreckage: Draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)