{T}: Add {R}{R}{R}. Spend this mana only to cast creature spells. If that mana is spent on a creature spell, it enters with an additional haste counter and decayed counter on it.

{5}: Lightspeed Cruiser becomes an artifact creature until end of turn.
Crew 2

Attacking creatures you control have first strike.
Whenever you amp it up, draw a card.

Lightvein Arrow deals 3 damage to any target. Scry 1.

Enchant land
When Lightvein Discovery enters, put a +1/+1 counter on target creature you control.
Enchanted land has “{T}: Add two mana of different colors.”

Untap target creature. It gets +2/+2 and gains indestructible until end of turn.

{T}: Target land you control becomes a 4/4 Elemental creature with lifelink, haste, and “When this creature dies, draw a card.” It's still a land. Sacrifice it at the beginning of the next end step.

Menace
Other Elementals you control have menace.

Whenever Lithe Stalker or another artifact you control enters, artifact creatures you control gain first strike until end of turn.

{1}, {T}: Add one mana of any color.
{2}, Sacrifice Living Compass: Draw a card.

Enchant creature
Enchanted creature gets +2/+2.
Wander {2}{W}

Create a 2/2 blue Drake creature token with flying.
Whenever a creature you control enters, if it wandered, you may exile Lofty Frontiers from your graveyard. If you do, create a 2/2 blue Drake creature token with flying.

Flying
When Lofty Voter enters, make a pledge.

Solidarity
Londel Sharpshot can't be blocked by creatures with power 2 or less.

Whenever this creature transforms into Lone Switchblade or another permanent you control transforms, each opponent loses 1 life and you gain 1 life.

Put any number of target noncreature cards from your graveyard on top of your library in any order.
Draw a card, then exile Long-Lost Legacy.

Looming Skyscrapers enters tapped.
{T}: Add {B} or {G}.
{4}: Make a pledge. Activate only as a sorcery.

Menace
{B}{R}: Target creature with power 4 or less can't be blocked by more than one creature this turn.

Kraken, Leviathan, Octopus, and Serpent spells you cast cost {X} less to cast, where X is your devotion to blue.

When Lost Resistor dies, you gain 1 life.
Cybersoul {X}{X}{W}

Create X blue Shrine enchantment tokens named Unmarked Shrine with “At the beginning of your upkeep, each opponent mills a card.”
{1}{U}, Exile Lost to Memory from your graveyard: Draw two cards. Activate only if an opponent has eight or more cards in their graveyard.

Before equipped creature would assign, deal, or be dealt damage, sacrifice Lum Berry. If you do, equipped creature gets +1/+1 until end of turn.
When you sacrifice Lum Berry, you may exile equipped creature, then return that card to the battlefield under its owner's control. Put a +1/+1 counter on it.
Equip {1}

Lunar Plateau enters tapped.
{T}: Add {W} or {B}.
{1}, Discard Lunar Plateau: Scry 2.

Integrate the top two cards of target player's library. They lose 2 life, and you gain 2 life.
Whenever a permanent you control with two or more cards integrated onto it dies, you may pay {B}. If you do, return Lure into Lunacy from your graveyard to your hand.

Menace
Drop — Lurking Glitch enters with two +1/+1 counters on it if you didn't cast any creature spells during your last turn.