Leonin Scimitar

Artifact — Equipment

Equipped creature gets +1/+1.
Equip (: Attach to target creature you control. Equip only as a sorcery.)

Library of Leng

Artifact

You have no maximum hand size.
If an effect causes you to discard a card, discard it, but you may put it on top of your library instead of into your graveyard.

Lifespark Spellbomb

Artifact

, Sacrifice Lifespark Spellbomb: Until end of turn, target land becomes a 3/3 creature that's still a land.
, Sacrifice Lifespark Spellbomb: Draw a card.

Lightning-Core Excavator

Artifact Creature — Golem (0/3)

, , Sacrifice Lightning-Core Excavator: It deals 3 damage to any target.

Locthwain Gargoyle

Artifact Creature — Gargoyle (0/3)

: Locthwain Gargoyle gets +2/+0 and gains flying until end of turn.

Luxior, Giada's Gift

Legendary Artifact — Equipment

Equipped creature gets +1/+1 for each counter on it.
Equipped permanent isn't a planeswalker and is a creature in addition to its other types. (Loyalty abilities can still be activated.)
Equip planeswalker
Equip

Magma Mine

Artifact

: Put a pressure counter on Magma Mine.
, Sacrifice Magma Mine: It deals damage equal to the number of pressure counters on it to any target.

Mana Cylix

Artifact

, : Add one mana of any color.

Mana Screw

Artifact

: Flip a coin. If you win the flip, add . Activate only as an instant.

Masterwork of Ingenuity

Artifact — Equipment

You may have Masterwork of Ingenuity enter the battlefield as a copy of any Equipment on the battlefield.

Maze Skullbomb

Artifact

, Sacrifice Maze Skullbomb: Draw a card.
, Sacrifice Maze Skullbomb: Target creature you control gets +3/+3 and gains trample until end of turn. Draw a card. Activate only as a sorcery.

Metallic Sliver

Artifact Creature — Sliver (1/1)

Mishra's Research Desk

Artifact

, , Sacrifice Mishra's Research Desk: Exile the top two cards of your library. Choose one of them. Until the end of your next turn, you may play that card.
Unearth (: Return this 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.)

Mossfire Egg

Artifact

, , Sacrifice Mossfire Egg: Add . Draw a card.

Multiclass Baldric

Artifact — Equipment

Equipped creature has lifelink if you control a Cleric, deathtouch if you control a Rogue, haste if you control a Warrior, and flying if you control a Wizard.
As long as you have a full party, prevent all damage that would be dealt to equipped creature.
Equip

Myr Mindservant

Artifact Creature — Myr (1/1)

, : Shuffle your library.

Myr Moonvessel

Artifact Creature — Myr (1/1)

When Myr Moonvessel dies, add .

Myr Scrapling

Artifact Creature — Myr (1/1)

Sacrifice Myr Scrapling: Put a +1/+1 counter on target creature.

Navigator's Compass

Artifact

When Navigator's Compass enters the battlefield, you gain 3 life.
: Until end of turn, target land you control becomes the basic land type of your choice in addition to its other types.

Necrogen Spellbomb

Artifact

, Sacrifice Necrogen Spellbomb: Target player discards a card.
, Sacrifice Necrogen Spellbomb: Draw a card.