msem-instigator

{8}: Create eight 1/1 blue Tentacle creature tokens.
{8}: Counter target spell unless its controller pays {8}.
{8}: Draw eight cards.

Enchant player
Whenever enchanted player becomes the target of a spell or ability they don't control, if it isn't a copy, its controller copies it.

Concord — When Palace Servant enters, if there are four or more card types among permanents you control, create two 1/1 white Merfolk creature tokens.

Flying
Whenever Pale Courier deals combat damage to a player, it voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Pale Courier phases in, create a 1/1 white Dwarf creature token.

You may play Paradise Reef from your graveyard as long as seven or more cards are in your graveyard.
Paradise Reef enters tapped.
{T}: Add {G} or {W}.
Cycling {1}{G}{W} ({1}{G}{W}, Discard this card: Draw a card.)

Enchant opponent
When Pathless Shallows enters, exile target creature enchanted player controls until Pathless Shallows leaves the battlefield.
Enchanted player can't cast spells with the same name as the exiled card.

Vigilance
{2}{W}: Patrol Ship gets +0/+3 until end of turn. Activate only once each turn.
Cycling {2/W} ({2/W}, Discard this card: Draw a card.)

Prowess
Whenever you cast your first instant or sorcery spell from your hand during each of your turns, if it doesn't have compose, it gains compose. (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Target opponent reveals their hand. You choose a nonland card from it. If you can't, they discard a card. Otherwise, that player discards a card, then if they didn't discard the chosen card, you create a tapped Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Gain control of up to two target creatures or planeswalkers until end of turn. Untap them. They gain haste until end of turn. Pay the Right Price deals 3 damage to each of them at the beginning of the next end step.

Look at the top five cards of your library. You may reveal an enchantment, instant, or sorcery card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

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.

When Pensive Muse enters, create a white Aura enchantment token named Seal's Love attached to target creature you control. The token has enchant creature and “Enchanted creatures you control get +1/+1.”

When Pensive Songwriter enters, you may copy and then exile an instant or sorcery card with mana value 2 or less from your hand. Cast the copy without paying its mana cost. You may cast the card as long as it remains exiled.

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.

Target player discards two cards. Forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

Deathtouch
When Pestilent Scavenger enters, you may mill three cards.

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.)

Flying
Whenever Phantasmal Owl attacks, it gets +1/+1 until end of turn for each other creature you control with flying.

Return X target creature cards with mana value 3 or less from your graveyard to the battlefield, then choose one of them and exile the rest.

Codex — Eleventh Hour Breakthrough; Mentorb; Ostracizer Orb; Possibility Engine; Sealed Riftway; Self Replication. (As this enters, conjure its contents into a shuffled face-up additional library.)
{T}, Sacrifice an artifact: Draw a card from the codex's library.

Destroy target creature or planeswalker. That permanent's controller loses 3 life unless that player sacrifices a nonland permanent or discards a card.

Target opponent reveals their hand. You choose a nonland card from it. That player discards that card. You lose 2 life unless that player is cursed.

Choose highest or lowest. Target opponent reveals their hand and discards a card with the chosen kind of mana value among the revealed nonland cards.

When Pirate's Cutlass enters, attach it to target Pirate you control.
Equipped creature gets +2/+1.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)