msem-instigator

Pelagic Hydra enters with seven +1/+1 counters on it.
{1}{G}: Put a +1/+1 counter on Pelagic Hydra.
Remove a +1/+1 counter from Pelagic Hydra: It deals 1 damage to target creature blocking or blocked by it.

Equipped creature gets +1/+1 for each creature you control.
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)

{1}, Sacrifice Penny Dreadful: Target creature can't attack or block this turn.
{1}, Sacrifice Penny Dreadful: Draw a card.

Madness {4}{G} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)
Target creature gets +4/+4 until end of turn. Put a trample counter on it. If this spell's madness cost was paid, all creatures able to block that creature this turn do so.

Perfect Aim deals 5 damage to target creature with flying. When that creature dies this turn, you gain 5 life.

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever you cast your second spell each turn, add a quest counter.
Exile the top card of your library. You may play that card until the end of your next turn.
The second spell you cast during your next turn cost {1} less to cast.
You may cast target instant or sorcery card from your graveyard this turn. When you do, copy it. You may choose new targets for the copy.

{1}{R}: Performer of Desire gets +1/+1 and gains menace until end of turn. Then if its power is 4 or greater, you may transform it.

{T}: Add {G}. When that mana is used to cast a spell with mana value 5 or greater, you may untap Performer of Growth and transform it.

{T}: Add {C}.
{1}, {T}, Sacrifice Perilous Passage: Destroy target nonbasic land. Activate only if an opponent controls four or more lands.

Exile target land. Create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Trample
When Pernicious Primavore enters or dies, destroy up to three target artifacts and/or enchantments.

Untap all artifacts you control during each other player's untap step.
Tap two untapped artifacts you control: Target player mills two cards.

Whenever a spell or ability with one or more targets is put onto the stack, reselect its targets at random.

Petal Blade deals 2 damage to target attacking or blocking creature. Create a Treasure token.

Whenever another creature you control enters, put a +1/+1 counter on a creature you control.

When Petal Scatterer enters, create a green Aura enchantment token named Blossom attached to target land. It has enchant land and “Enchanted land has ‘{T}: Add {G}{G}.'”
Petal Scatterer gets +1/+1 for each noncreature, nonland permanent you control.

[+1]: You may play an additional land this turn.
[–1]: Discard a card. If you do, return target creature, land or sorcery card from your graveyard to your hand.
[–5]: Create Thrice-Folded Lotus, a colorless Masterpiece artifact token with “{T}: Add three mana of any one color.” and “{3}, {T}: This artifact deals 3 damage to any target.”

Whenever a noncreature permanent enters, Petaldiver deals 1 damage to that permanent's controller.

Exile two cards from your graveyard: Petrified Guard becomes a 3/1 Zombie creature until end of turn.

Target creature you control gets +2/+0 until end of turn. It fights target creature you don't control. (Each deals damage equal to its power to the other.)

Colossal 2—{1}{G}{G} (You may cast this for its colossal cost to have it enter with two +1/+1 counters; or pay {1}{G}{G} as a sorcery: Put two +1/+1 counters on it if it has none.)
Whenever a permanent you control with a counter on it becomes the target of a spell or ability an opponent controls, draw a card.

At the beginning of your end step, if there are three or more creature cards in your graveyard, put a +1/+1 counter on target creature you control.

When Phasmopillar enters, search your library for a creature card with mana value 5 or greater, reveal it, put it into your hand, then shuffle. If a creature card with mana value 9 or greater was revealed this way, put two +1/+1 counters on Phasmopillar.

Heroic — Whenever you cast a spell that targets Pheres-Band Courser, put a +1/+1 counter on Pheres-Band Courser.

Whenever a source you control deals damage to an opponent this turn, exile the top card of your library. You may play it this turn.