Merchant Ship can't attack unless defending player controls an Island.

Whenever Merchant Ship attacks and isn't blocked, you gain 2 life.

When you control no Islands, sacrifice Merchant Ship.

As an additional cost to cast this spell, sacrifice a creature or land.

Draw two cards.

Flying

Whenever Merfolk Windrobber deals combat damage to a player, that player mills a card. (They put the top card of their library into their graveyard.)

Sacrifice Merfolk Windrobber: Draw a card. Activate only if an opponent has eight or more cards in their graveyard.

Cumulative upkeep (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

, Discard a card: Draw a card.

This spell costs less to cast, where X is the total mana value of noncreature artifacts you control.

Sacrifice two artifacts: Return Metalwork Colossus from your graveyard to your hand.

Whenever Mezzio Mugger attacks, exile the top card of each player's library. You may play those cards this turn, and you may spend mana as though it were mana of any color to cast those spells.

Blitz (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

As an additional cost to cast this spell, sacrifice X Contraptions.

Assemble X plus one Contraptions. (To assemble a Contraption, put the top card of your Contraption deck face up onto one of your sprockets.)

At the beginning of your upkeep, you may put a verse counter on Midsummer Revel.

, Sacrifice Midsummer Revel: Create X 3/3 green Beast creature tokens, where X is the number of verse counters on Midsummer Revel.

As an additional cost to cast this spell, sacrifice a creature.

Target player reveals their hand and discards all cards of each of the sacrificed creature's colors.

, Sacrifice a creature: Target opponent reveals their hand. You choose a card from it. That player discards that card. Activate only as a sorcery.

If you control a Swamp, you may sacrifice a creature rather than pay this spell's mana cost.

Each player exiles two cards from their hand.

Exploit (When this creature enters the battlefield, you may sacrifice a creature.)

When Mindleech Ghoul exploits a creature, each opponent exiles a card from their hand.

, , Sacrifice Mindslaver: You control target player during that player's next turn. (You see all cards that player could see and make all decisions for the player.)

All Slivers have ", Sacrifice this permanent: Target player discards a card at random. Activate only as a sorcery."

If it's your turn, you may sacrifice a Mountain rather than pay this spell's mana cost.

Mine Collapse deals 5 damage to target creature or planeswalker.

Enchant nonland permanent

Enchanted permanent is a Treasure artifact with ", Sacrifice this artifact: Add one mana of any color," and it loses all other abilities. (If it was a creature, it's no longer a creature.)

Whenever a nontoken creature enters the battlefield under your control, you may pay . If you do, create a token that's a copy of that creature, except it has haste and "At the beginning of the end step, sacrifice this permanent."

When Minotaur Explorer enters the battlefield, sacrifice it unless you discard a card at random.

When Minsc & Boo, Timeless Heroes enters the battlefield and at the beginning of your upkeep, you may create Boo, a legendary 1/1 red Hamster creature token with trample and haste.

+1: Put three +1/+1 counters on up to one target creature with trample or haste.

−2: Sacrifice a creature. When you do, Minsc & Boo, Timeless Heroes deals X damage to any target, where X is that creature's power. If the sacrificed creature was a Hamster, draw X cards.

Minsc & Boo, Timeless Heroes can be your commander.

Each opponent sacrifices a creature or enchantment.

: Add .

, , Sacrifice a creature: You gain life equal to the sacrificed creature's toughness.

Mirror Mirror enters the battlefield tapped.

, , Sacrifice Mirror Mirror: Choose target player. At the beginning of the next end step, exchange life totals with that player, exchange control of all permanents you and that player control, and exchange cards in your hands, cards in your libraries, and cards in your graveyards.

, Sacrifice Mirror Universe: Exchange life totals with target opponent. Activate only during your upkeep.

Target player sacrifices a permanent.

Permanents you control have "Ward—Sacrifice a permanent."

Each artifact card in your graveyard has unearth . (: Return the card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

, Sacrifice Mishra's Groundbreaker: Target land becomes a 3/3 artifact creature that's still a land. <I>(This effect lasts indefinitely.)</I>

Flying, first strike

At the beginning of each other player's upkeep, you may compliment that player on their game play. If you don't, sacrifice Miss Demeanor.

Flash

Flying

Champion a Faerie (When this enters the battlefield, sacrifice it unless you exile another Faerie you control. When this leaves the battlefield, that card returns to the battlefield.)

When a Faerie is championed with Mistbind Clique, tap all lands target player controls.

Whenever you cast an Aura or Equipment spell, put a +1/+1 counter on Mister Gutsy.

When Mister Gutsy dies, create X Junk tokens, where X is the number of +1/+1 counters on it. (They're artifacts with ", Sacrifice this artifact: Exile the top card of your library. You may play that card this turn. Activate only as a sorcery.")

Flying

Whenever you cast a spell from anywhere other than your hand, you may pay . If you do, copy that spell and you may choose new targets for the copy. If the copy is a permanent spell, it gains haste and "At the beginning of your end step, sacrifice this permanent." (A copy of a permanent spell becomes a token.)

, Sacrifice Mnemonic Sphere: Draw two cards.

Channel — , Discard Mnemonic Sphere: Draw a card.

When another creature enters the battlefield, sacrifice Mogg Bombers and it deals 3 damage to target player or planeswalker.

Sacrifice Mogg Mob: It deals 3 damage divided as you choose among one, two, or three targets.

Echo (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

When Mogg War Marshal enters the battlefield or dies, create a 1/1 red Goblin creature token.

When Mold Demon enters the battlefield, sacrifice it unless you sacrifice two Swamps.

At the beginning of each player's upkeep, that player sacrifices an artifact.

At the beginning of your upkeep, sacrifice Molten-Tail Masticore unless you discard a card.

, Exile a creature card from your graveyard: Molten-Tail Masticore deals 4 damage to any target.

: Regenerate Molten-Tail Masticore.

As an additional cost to cast this spell, sacrifice a creature.

You draw cards equal to the sacrificed creature's power, then you gain life equal to its toughness.

When a creature enters the battlefield, sacrifice Monkey Cage and create X 2/2 green Monkey creature tokens, where X is that creature's mana value.

Sacrifice Moonglove Extract: It deals 2 damage to any target.

, , Sacrifice Moonsilver Key: Search your library for an artifact card with a mana ability or a basic land card, reveal it, put it into your hand, then shuffle.

As an additional cost to cast this spell, sacrifice an artifact or creature.

Draw cards equal to the mana value of the sacrificed permanent.

Sacrifice Morgue Thrull: Mill three cards.

Flying

Cumulative upkeep—Pay 1 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

As an additional cost to cast this spell, sacrifice a creature or pay .

Menace (This creature can't be blocked except by two or more creatures.)

You have no maximum hand size.

At the beginning of your upkeep, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this artifact: Draw a card.")

Whenever you draw your second card each turn, put two +1/+1 counters on Morska, Undersea Sleuth.

Living weapon (When this Equipment enters the battlefield, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)

Equipped creature gets +0/+1 and has "Sacrifice this creature: This creature deals 1 damage to any target."

Equip

, Discard a card: Exile target card from a graveyard.

, Sacrifice Mortiphobia: Exile target card from a graveyard.

Whenever a creature an opponent controls dies, sacrifice Mother of Goons unless you insult that creature.

Mountain Valley enters the battlefield tapped.

, Sacrifice Mountain Valley: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.