msem-instigator

Put target creature into its owner's library third from the top.

Cast this spell only during the declare blockers step.
After this step there's an additional declare attackers step followed by an additional declare blockers step. (A creature can't attack or block again if it's already attacking or blocking.)
Draw a card.

Menace
At the beginning of your upkeep, if an opponent has more cards in hand than you, you draw a card and you lose 1 life.

[+2]: Target player exiles a card from their hand at random. Until the end of that player's next turn, they may play that card.
[0]: Gain control of target creature or planeswalker until end of turn. Tap it.
[–9]: Take an extra turn after this one. During that turn, you control all opponents.

[+2]: Create a Vial token. (It's an artifact with “1, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
[–3]: Sacrifice another nonland permanent. If you do, destroy target nonland permanent.
[–9]: You get an emblem with “At the beginning of your end step, create Fallen One, a legendary 6/6 black Faerie Angel Avatar creature token with flying.”

Noncreature spells your opponents cast cost {1} more to cast.
Unveil {2}{W}{U} ({2}{W}{U}: Transform this. Unveil only as a sorcery.)

Other creatures you control get +2/+0 and have menace.
Whenever another creature you control dies, if it wasn't sacrificed, sacrifice a creature.

You may play an additional land on each of your turns.
Landfall — Whenever a land you control enters, draw a card.

You may play an additional land on each of your turns.
{4}{U}{U}: Transform Misthollow Rites. Activate only as a sorcery.

Poisonous 1 (Whenever this creature deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)
At the beginning of your upkeep, if an opponent is poisoned, you draw a card, you lose 1 life, and you get a poison counter.

Mistwake Hydra enters with X +1/+1 counters on it.
Creatures with power less than Mistwake Hydra's power can't block it.

Misty Churchyard enters tapped.
{T}: Add {W}.
{1}{W}{W}: Until end of turn, Misty Churchyard becomes a 1/4 Cleric creature with “Whenever this creature is dealt damage, put that many +1/+1 counters on it.” Activate only if you're horrific.

Flying, haste
Miyoga Flameweaver can't block.
Whenever Miyoga Flameweaver attacks, exile the top card of your library. You may play that card until end of turn.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Flying
{2}{U}{U}: Wizard — Draw a card, then discard a card. Mizuki gains “Noncreature spells you cast cost {1} less.”
{6}{U}{U}: Avatar — Draw two cards. Mizuki gains “Whenever Mizuki attacks, you may cast a noncreature spell from your hand without paying its mana cost.”

Other creatures you control get +2/+2.

Creatures you control with flying get +1/+1.
Whenever a creature you control with flying deals combat damage to a player, you may pay {U}. If you do, draw a card.

Create a token that's a copy of target creature you control.
Fabled {5}{U}{U} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

Prowess
Libraries can't be searched.
Spells you cast cost {1} less to cast for each permanent you control but don't own.

Flash
When Mokuteki Ambusher enters, until end of turn, other creatures you control gain “{T}: This creature deals 1 damage to any target.”

{T}: Add {G}.
Once during each of your turns, you may cast a creature spell from your graveyard if there are thirteen or more cards in your graveyard. (You still pay its costs. Timing rules still apply.)

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
Double strike
If this creature would deal noncombat damage, it deals double that damage instead.

Whenever you cast a noncreature spell, put a hatch counter on Molten Incubation. Then if it has five hatch counters on it, sacrifice it and choose one —
• Create a 5/5 red Dragon creature token with flying.
• Molten Incubation deals 20 damage to each creature.

Molten Mire enters tapped unless you control a basic land.
{T}: Add {B} or {R}.

Molting Abomination can't be blocked by creatures with power 2 or less.
Whenever Molting Abomination deals combat damage to a player or planeswalker, create a tapped 3/2 colorless Horror creature token. Put a stun counter on that token. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Cast this spell only during your turn.
Counter target spell.