msem-instigator

Counter target instant spell.

Harmony — Exile another target creature until Pretentious Performer leaves the battlefield.
When Pretentious Performer enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Wary Rider has first strike as long as its attacking.
Wary Rider gets +1/+0 as long as you control two or more other creatures.

When Cobbled Currency enters, discard a card, then draw a card.
{3}, Sacrifice Cobbled Currency: Discard two cards, then draw two cards.

At the beginning of combat on your turn, Ruination's Hand gains flying until end of turn if a creature you control or a creature card in your graveyard has flying. The same is true for first strike, double strike, deathtouch, hexproof, haste, indestructible, lifelink, menace, reach, trample, and vigilance.

Flash
Flying
When Seeker Amalgam enters, you may counter target spell with mana value less than or equal to the number of Elementals you control.

Flash
If a spell or ability would cause an opponent to create a token, instead you create that token and that player creates a 1/1 blue Fish creature token.

Draw three cards, then manifest a card from your hand. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

As Fortified Village enters, you may reveal a Forest or Plains card from your hand. If you don't, Fortified Village enters tapped.
{T}: Add {G} or {W}.

Primal {1}{B}{B} (During your turn, you may cast this spell for {1}{B}{B} instead of playing a land.)
Deathtouch
When Venomous Gorran enters, if you cast it for its primal cost, it fights target creature.

Augmented — Whenever you cast a spell from your hand, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, exile cards from the top of your library until you reveal a nonland card with mana value less than that spell's mana value. You may cast that card without paying its mana cost. Put the revealed cards not cast this way on the bottom of your library in a random order.

Return target instant or sorcery card from your graveyard to your hand. Then if this spell wasn't foretold, discard a card.
Exile Spark of Inspiration.
Foretell {R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

When Maghbri Whisper enters, nourish 1. (To nourish 1, either put a +1/+1 counter on this creature or create a 1/1 white Citizen creature token.)
Sacrifice a creature: Maghbri Whisper gets +2/+2 until end of turn.

Target creature gets +1/+5 until end of turn.
Draw a card.

Draw two cards. Each opponent loses 2 life and you gain 2 life.
Flashback {4}{U}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Whenever a creature you control phases in, it gets +2/+2 until end of turn.

At the beginning of your upkeep, if you don't control any Imps, you may pay {B}. If you do, create a 1/1 black Imp creature token.
Sacrifice a creature: Each opponent loses 1 life.

As an additional cost to cast this spell, discard a card.
Draw two cards. Gift of the Phoenix deals 2 damage to you.

Whenever you cast a creature spell, you may return target nontoken creature you control with a different name to its owner's hand. If you do, copy that spell. (A copy of a creature spell becomes a token.)

({T}: Add {W} or {U}.)
Bustling Harbor enters tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Ferocious — Whenever a creature with power 4 or greater you control enters, you gain 4 life.

Determined Chevalier has vigilance as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Flying, trample
Whenever Bretala of Redsky attacks, it gains double strike until end of turn unless defending player sacrifices a creature.

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
[+1]: Create a 2/2 blue Elemental Illusion creature token with flying and “Whenever this becomes the target of a spell, sacrifice it.”
[–3]: Return up to one other target nonland permanent to its owner's hand. Draw a card.

Choose target creature you control. Double its power and toughness until end of turn. That creature deals X damage divided as you choose among any number of target creatures and/or planeswalkers your opponents control, where X is its power.