msem-instigator

Reveal the bottom card of your library. You may put it on top of your library. Target creature gets -0/-X until end of turn, where X is that card's mana value.

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.)

When Grave Wrangler enters, you may return target creature card from your graveyard to your hand.

Vigilance
Whenever Cai Lan, the Chained perseveres, exile target creature an opponent controls until Cai Lan leaves the battlefield. (A creature perseveres when it survives damage.)

Whenever Dauntless Qith becomes the target of a spell or ability, Dauntless Qith gains double strike until end of turn.

When target creature you control dies this turn, create a token that's a copy of it, except it has no mana cost.

At the beginning of your upkeep, if you control four or more Swamps, you may exile target creature card from your graveyard. If you do, create a tapped token that's a copy of it except it's a black Mummy.

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]: Up to one other target permanent gains hexproof until your next turn. Untap it.
[–3]: Put target nonland permanent into its owner's library third from the top.
[–8]: Shuffle any number of cards you own from your graveyard and/or outside the game into your library. You get an emblem with “Permanents you control have ‘{T}: Draw a card.'”

Choose one —
• Destroy target creature with flying.
• Target creature you control gets +2/+2 until end of turn.

Choose one—
• Target creature gets -3/-3 until end of turn.
• All creatures get -1/-1 until end of turn.

When Seductive Seashell enters, target player mills two cards.
{2}, Sacrifice Seductive Seashell: Target player mills four cards.

Rakkiri Archer gets +0/+1 and has reach as long as it's embattled. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Draw a card.
Reprise {2} (As you cast an instant or sorcery spell, you may exile one card with reprise from your graveyard and pay its reprise cost. If you do, add its effects to that spell.)

Sunspear Surge deals 2 damage to target creature and 1 damage to each other creature.

Flying
When Hostile Barbfly enters, you may have it consume. When you do, target creature gets -2/-2 until end of turn. (To consume, sacrifice another creature or exile a creature card from your graveyard.)

Creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, Bellowing Thoctar gets +2/+2 until end of turn.

({T}: Add {G} or {U}.)
Rainforest Spring enters tapped.

Add three mana of any one color.

When Coralight Mystic enters, create a white Aura enchantment token named Whale's Spirit attached to target creature. The token has enchant creature and “Enchanted creature has lifelink.”

When Cave Eel enters, look at the top three cards of your library. Put one on top and the rest on the bottom in any order.

Menace
Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, each opponent discards a card.

You may have Graveborn Usurper enter as a copy of any creature card in a graveyard, except it has “{2}{U}{B}, Exile a creature card from a graveyard: Graveborn Usurper becomes a copy of the exiled card, except it has this ability.”

This spell costs {2} less to cast if you've cast a blue noncreature spell this turn. The same is true for a red noncreature spell.
Menace

Invigorate 1, then untap each creature you control with a +1/+1 counter on it. (Choose a creature with the least power among creatures you control and put a +1/+1 counter on it.)