msem-instigator

Haste
Whenever another creature you control dies, each opponent loses 1 life and you gain 1 life.

{B}{G}, {T}: Reveal the bottom card of your library and exile it. Target creature gets +X/-X until end of turn, where X is that card's mana value.

Augmented — At the beginning of each end step, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on Defected Explorer.

Whenever you scry, tap target creature an opponent controls.
{2}{W}{U}: Scry 1. You gain 1 life.

At the beginning of your upkeep, choose a creature. Its controller may sacrifice it. If that player doesn't, you gain life equal to its power.

{2}{U}{B}: Return Depth Charger to its owner's hand. If you do, return target creature to its owner's hand. That player discards a card.

Target permanent you control gains protection from your opponents until end of turn.
Draw a card.

Once each turn, when you foretell a card or cast a foretold spell, you may create a 1/1 blue Rogue creature token.
{1}{U}{B}: Draw a card, then discard a card.

Whenever you create one or more tokens, put a rift counter on Destabilizing the Rifts.
As long as Destabilizing the Rifts has seven or more rift counters on it, creature tokens you control can't leave the battlefield.

{2}, {T}: Exile target creature. Return that card to the battlefield under its owner's control at the beginning of the next end step. Activate only as a sorcery.

Counter target monocolored spell. Its controller loses 2 life.

Exile the top two cards of your library. Until your next end step, you may play those cards.
Breakthrough — Whenever you cast your third spell each turn, you may exile Devoted Artistry from your graveyard. If you do, you may cast a copy of it at the beginning of your next upkeep. (You still pay its costs.)

Other enchantments you control have hexproof.
At the beginning of your upkeep, you gain 1 life and exile up to one target card from a graveyard.

Concord — {T}, Sacrifice Disciple of Destruction: Destroy target nonland permanent. Activate only if there are four or more card types among permanents you control.

Whenever you cast a legendary spell, each opponent loses 1 life and you gain 1 life.
{W}{B}, Sacrifice a legendary nonland permanent: Draw two cards.

Target creature you control gains deathtouch until end of turn. It fights another target creature.

{2}{U}{B}, Sacrifice a creature: Return target creature card from your graveyard to the battlefield with a finality counter on it. It gains myriad. (Whenever it attacks, for each opponent other than defending player, you may put a token that's a copy of this creature onto the battlefield tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

When Dream Keeper enters the battlefield, each player conjures a card named Fatigue and puts it on top of their library. (It's a colorless sorcery that costs {2} with “Draw a card.”)
Whenever a player draws a card except the first one they draw in each of their draw steps, each opponent mills a card.

Each player mills five cards.
Coalesce {4}{U}{B} (You may cast this from your graveyard for {4}{U}{B}. If you do, put it onto the battlefield as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Drink Thoughts Like Oil can't be blocked.

Double strike
{3}{R}{W}: Create Hao'Tai's Blessing, a legendary red and white Aura enchantment token with enchant creature and “Enchanted creature gets +3/+3 and has flying” and attach it to Duan, the Fabled Rider.

When Duchess Odelia VII enters the battlefield, search your library for a nonland permanent card with mana value 1 or less, reveal it, put it into your hand, then shuffle.

First strike, menace
Whenever Dueling Duo or another creature you control becomes blocked, that creature deals 1 damage to each creature blocking it.

As Duke Gerard Hoff enters the battlefield, an opponent gains control of it.
Duke Gerard Hoff can't attack its owner or planeswalkers that player controls.
Creatures your opponents control get +2/+1.

Whenever Eclipse Knight attacks, each opponent loses 1 life. You gain life equal to the life lost this way.
Eclipse Knight gets +1/+1 as long as you have 10 or more life than your starting life total.
Eclipse Knight gets +1/+1 as long as an opponent has 10 or less life than their starting life total.

Whenever you cast an artifact or enchantment spell, scry 1, then create a 1/1 white Merfolk creature token.
Whenever you cast a Merfolk spell, look at the top card of your library. If it's an artifact or enchantment card, you may reveal it and put it into your hand.