msem-instigator

This spell costs {1} less to cast for each legendary creature you control.
Search your library for a legendary creature card with mana value X or less, put that card onto the battlefield, then shuffle.

When Confining Priest enters, exile another target creature with power 4 or less an opponent controls until Confining Priest leaves the battlefield. (That creature returns under its owner's control.)

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
When Dancer of the Great Current enters, tap up to one target creature. If you control two or more other creatures that are Merfolk, Wizards, or Rogues, instead return that creature to its owner's hand and put a +1/+1 counter on Dancer of the Great Current.

At the beginning of combat on each opponent's turn, if you control three or more enchantments, choose target creature. Prevent all combat damage that creature would deal this turn.
{2}{W}: You gain 2 life and scry 1.

Repeat the following process X times. Reveal the top two cards of your library. Put one of them into your hand and the other into your graveyard.

[+1]: Emperor Tzhai deals 1 damage to each creature, planeswalker, and opponent you don't control.
[0]: Target creature can't attack you or Emperor Tzhai until Emperor Tzhai leaves the battlefield.
[–10]: You control target player.

{T}: Add {C}.
{T}, Sacrifice Gilded Gulch: Add one mana of any color.
When you discard Gilded Gulch, you may pay {1}. If you do, create a tapped colorless land token named Fading Rift with “{T}, Sacrifice this land: Add one mana of any color.”

Wu Xing (Add effects based on the number of colors of mana spent to cast this spell.)
1 | Discard up to two cards, then draw that many cards plus one.
3 | For each color of mana spent to cast this spell, add one mana of that color.

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.

Flash
When Qililia's Scavenger enters, look at the top six cards of your library. You may put a Merfolk card with lesser mana value from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
Other Merfolk you control get +1/+1.

Draw a card, then draw cards equal to the number of cards named Sea Cache in your graveyard.

When Serafina's Gift enters, if you cast it, target opponent gains control of it.
At the beginning of your upkeep, draw three cards, then discard two cards.

Each creature gets -X/-X until end of turn. Destroy each artifact and enchantment with mana value X or less.

You draw a card and you lose 1 life. Exile Small Luxuries.
At the beginning of your upkeep, you may return Small Luxuries from your graveyard to your hand.

Exile target creature. Its controller reveals cards from the top of their library until they reveal a creature card. The player puts that card onto the battlefield, then shuffles all other cards revealed this way into their library.

Whenever one or more creatures die for the first time each turn, you draw a card and you lose 1 life.
Whenever you cast a black noncreature spell, Villainy deals 2 damage to any target and you gain 2 life.