msem-instigator

Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Exile the top three cards of your library. Cast a spell with mana value X or less from among them without paying its mana cost.

When Mettalia's Forward enters, you may salvage a card. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

Engage (This creature must be blocked each combat if able.)
{R}: Mettlesome Watchkeeper gets +1/+0 until end of turn.

Whenever a land you control enters, crystallize.
{10}: Shuffle any number of other permanents you control into their owner's library. Mill that many cards. Put all permanents cards milled this way onto the battlefield. Activate only during your turn and only once each turn.

Mianju enters with your choice of a menace or +1/+1 counter on them.
Whenever two or more creatures in Mianju's pack attack, mill three cards, then return a creature card from your graveyard to your hand. (Two or more creatures you control with equal power are in a pack.)

Create a 2/2 blue Jellyfish enchantment creature token with flying.
Flashback {4}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

When Miasma Spewer enters, you may sacrifice a permanent. When you do, Miasma Spewer deals 1 damage to each opponent and each creature and planeswalker they control.

Whenever you discard a card, choose up to one that hasn't been chosen this turn —
• Draw a card.
• Tap target creature. Put a stun counter on it.
• Create a 2/2 blue Jellyfish enchantment creature token with flying.

Flash
Wanderlust — When Microzoologist enters, search your library for a creature card with mana value 1. If you control four or more differently named lands, you may search for a creature card with mana value 3 or less instead. Reveal that card, put it into your hand, then shuffle.

Vigilance
When Mid-Autumn Celebrants enters, create a 2/2 white Panda Bear Monk creature token with vigilance.

Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.
{2}{B}: Create a 1/1 black Rat creature token with “This creature can't block.” Activate only if there are five or more creature cards in your graveyard.

Enchant opponent
Whenever Middleware or another Curse becomes attached to enchanted player, exile the top card of that player's library face down. For as long as that card remains exiled, you may look at it and you may play it. Mana of any type can be spent to cast that spell.

Target opponent discards two cards, then sacrifices a creature.

({T}: Add {B}.)
As Midnight Gate enters, you may pay 1 life. If you don't, Midnight Gate enters tapped.
Basic lands you control have “{T}: Add {B}.”

Look at the top two cards of your library. You may shuffle.
Draw two cards. You lose 2 life.

Flash

Harvest (You may tap any number of creatures you control as you cast this spell. If you do, reduce this spell's mana cost by their total power.)
Destroy target creature.

Whenever you cast a spell from exile, put two +1/+1 counters on Midnight Vagrant. It gains menace until end of turn.
{1}{B}{B}: Exile the top card of target opponent's library. You may play that card during any turn you attacked with a Rogue, and you may spend mana as though it were mana of any color to cast it. Activate only as a sorcery.

Flying
When Midnight Visitor enters, you may return target creature to its owner's hand.

Each player loses 2 life, discards two cards, sacrifices two creatures, then sacrifices two lands.

{T}, Mill a card: Add {G}.
{X}{U}{B}, {T}, Exile a permanent card with mana value X from your graveyard: Create a tapped token that's a copy of it, except it's an X/X Elemental creature in addition to its other types.

When Miede-District Alchemist enters, add {R}{R}{R}.
Paranoia {1}{R} (You may cast this spell for its paranoia cost when a permanent you control leaves the battlefield.)

Haste
{R}, {T}: Miede-District Enforcer deals 2 damage to target creature that entered this turn or player that cast a creature spell this turn.
Paranoia {1}{R} (You may cast this spell for its paranoia cost when a permanent you control leaves the battlefield.)

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{1}{R}: Mieng gains flying until end of turn.
Whenever Mieng attacks, create a 4/4 red Dragon creature token with flying that's tapped and attacking. Exile that token at end of combat unless you're in a renaissance.

Creatures you control gain flying until end of turn if you control a creature with flying. The same is true for first strike, double strike, haste, hexproof, indestructible, lifelink, trample, vigilance, and prowess.