msem-instigator

Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)
Whenever Merciless Exiled deals combat damage to a player, scry 2.

{T}: Draw a card, then discard a card.

Counter target spell unless its controller pays {2}. If that spell targets you or a permanent you control, counter that spell instead.

Enchant creature
Enchanted creature can't be blocked.
{1}{R}: Enchanted creature gets +1/+0 until end of turn.

{3}{R}: Attacking creatures you control get +1/+0 until end of turn.

{T}: Add one mana of color.
{3}{G}, {T}: Audition for green. Activate only as a sorcery. (Create a 1/1 Construct Actor creature token, a Scout Role giving 2/3 and vigilance, or a Warrior Role giving 3/2 and trample. Roles replace older ones.)

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.

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

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.

{B}, Sacrifice another creature: Surveil 1.

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.

Once each turn, when you activate a nonmana ability, you may create a tapped 1/1 white Spirit creature token with flying.
{4}{W}{U}: You gain 1 life and draw a card.

{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.

Choose one—
• Destroy target artifact.
• Target creature gets +4/+4 until end of turn.

Choose one —
• Destroy target artifact.
• You gain 4 life.

Search your library for a basic Forest or Plains card, put that card onto the battlefield tapped, then shuffle.
{3}{W}, Exile Migration Range from your graveyard: Create two 1/1 green and white Elk Spirit creature tokens. Activate only as a sorcery.

Vigilance
Whenever Mikkino becomes blocked by a creature with power 3 or greater, exile that creature.

When Militant's Standard enters, draw a card if you control a Merfolk.
Equipped creature gets +2/+1.
Equip {2}

Flying
Mind's Contagion has haste as long as there are two or more creature cards in your graveyard.
Whenever Mind's Contagion deals combat damage to a player, until your next turn, it gains “Noncreature spells opponents cast cost an additional 2 life to cast.”

As Mind-Mute enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.
{5}: Return Mind-Mute to its owner's hand.

Lifelink
Mind-Pryer gets +1/+1 as long as an opponent has one or fewer cards in hand.
Whenever an opponent discards a card, Mind-Pryer cackles. (Put a menace counter on it. If it already has menace, it deals 1 damage to each opponent instead.)

Mindhunter Grizzly can't attack or block unless you scried this turn.
{5}{U}: Scry 1.

Exile target spell. Then that card's owner may return it to their hand. If they do, draw a card.

When Mindwave Rod enters, attach it to target creature you control.
Equipped creature gets +1/+1 and has “Whenever this creature deals combat damage to a player, draw a card.”
Equip {2}

Mine Delver has first strike as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)