msem-instigator

Choose one —
• Counter target spell unless its controller pays {2}.
• Change the target of target spell with a single target unless that spell's controller pays {2}.

When Mana Potion enters, scry 1, then draw a card.
{2}, {T}, Sacrifice Mana Potion: Add two mana of any one color.

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Flying, vigilance
When Manafly enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

{T}: Add one mana of any color.

Pressure {G} (You may cast this spell for its pressure cost if there are seven or more cards in your graveyard.)
Deathtouch

When Manglehorn Hunter enters, draw a card and you lose 1 life.

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Flash
Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)

Maniac Macaque attacks each combat if able.
Whenever Maniac Macaque becomes blocked by a creature, Maniac Macaque deals 1 damage to that creature.

{T}: Discard two cards. If you do, draw two cards.

Manifest a creature card at random from your graveyard. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Add {R} and two mana of any one color.
When you next cast a spell this turn, Manifest Irrationality deals 3 damage to any target.

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)

Enchant creature
When Mantle of the Returned enters, return target creature card from your graveyard to the battlefield. It's a Zombie in addition to its other types.
Enchanted creature gets +1/+1 for each Zombie you control.

When Marauder's Broadsword enters, you may pay {1}. If you do, create a 1/1 white Soldier creature token and attach Marauder's Broadsword to it.
Equipped creature gets +2/+0.
Equip {2}

When Marauding Goliath becomes blocked by a creature with power 1 or less, sacrifice it at end of combat.

Civilized — When Marble Row Healer enters, if you control an artifact, a creature, and an enchantment, you gain 4 life.

Enchant creature
Enchanted creature gets +1/+1.
When enchanted creature dies, return another target creature card from your graveyard to your hand.

Target creature's controller judges it. Then if they honored it, you gain control of that creature until end of turn. Untap it. It gains haste until end of turn. (That creature's controller honors it by putting a +1/+1 counter on it or condemns it by sacrificing it to draw a card.)

Whenever Marine Delver attacks, draw a card.

{X}{U}{U}: Marine Monster can't be blocked by creatures with mana value X or less this turn.

Marinton Occultist can't block or be blocked.
Whenever one or more cards are put into a player's graveyard from their library, Marinton Occultist gets +1/+1 until end of turn.

You may return a land you control to its owner's hand rather than pay this spell's mana cost.
Marinton-Ravengulch Line enters tapped.
{T}: Add {B}.

When Marionette Phantom enters, choose one —
• Draw a card.
• Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)