msem-instigator

{T}: Target land you control becomes the basic land type of your choice until end of turn.
At the beginning of each end step, if you spent three or more colors of mana to cast spells this turn, surveil 1.

{T}: Add {U}. Spend this mana only to activate an ability or cast an instant or sorcery spell.

Landfall — Whenever a land you control enters, Landbound Connoisseur gets +1/+1 until end of turn, then you may have another target creature get +X/+X until end of turn, where X is Landbound Connoisseur's power.

Lantern-Bearer Belle gets +2/+0 and has flying as long as you've sacrificed a permanent this turn.

Tribute 1 (As this creature enters, an opponent of your choice may put a +1/+1 counter on it.)
When Lasis Persecutor enters, if tribute wasn't paid, it gains deathtouch. (This effect lasts indefinitely.)

Whenever Last Priest of Hadak attacks, you may discard a card. If you do, draw a card.
Whenever you discard a card, you may exile that card from your graveyard. During any turn you dealt damage to a player with a Dragon or Shaman, you may play that card.

First strike
{R}, Discard a land card: Put a +1/+1 counter on Lavamancer Adept. It gains menace until end of turn.

Whenever Leading Clergy attacks, you may pay {W}. If you do, audition for white. (Create a 1/1 Construct Actor creature token, a Scout Role giving 2/3 and vigilance, or a Cleric Role giving 2/2 and lifelink. Roles replace older ones.)

Whenever you cast an instant, sorcery, or Wizard spell, Leafdown Sizzlemage gets +1/+0 until end of turn.

When Leafguard Larva enters or a creature you control scavenges it, return target card from your graveyard to your hand.
Scavenge {3}{G} ({3}{G}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

{B}, {T}, Discard a card: Create a 1/1 black Skeleton creature token.
{B}, {T}, Sacrifice a creature: Put a +1/+1 counter on each Skeleton you control.

{T}: Exile two target creature and/or land cards from a graveyard. Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
{B}{G}, Sacrifice two Vials: Sacrifice Leticia Petrine, then return her to the battlefield transformed under her owner's control.

When Leyline Invoker enters and at the beginning of your upkeep, you may mill two cards.
{5}{B}, {T}, Sacrifice Leyline Invoker: Return target creature card from your graveyard to the battlefield. This ability costs {1} less to activate for each creature card in your graveyard.

Trample
Lian Taizi gets +1/+1 for each card in your hand.
When Lian Taizi enters, return any number of target cards with different mana values from your graveyard to your hand.

Lifelink
If a creature or planeswalker would die, instead exile it and put a +1/+1 counter on Librarian of Whispers.

When Life's Harbinger dies, you may put a +1/+1 counter on target creature you control.
{T}: Add {G}.

When Lifespark Alchemist enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Whenever Lifespark Alchemist or another creature dies, each opponent loses 1 life.

Whenever you activate a loyalty ability of a planeswalker, you gain 1 life.

When Lilyreed Triton enters, create a white Aura enchantment token named Triton's Gift attached to target creature. The token has enchant creature and “Enchanted creature gets +1/+0 and can't be blocked by creatures with power 3 or greater.”

When Lisa, the Daughter enters, create Mother, a legendary 4/1 black Demon creature token with flying and “This creature can't block.”
If a source would deal damage to Lisa while you control a Demon creature, instead that damage is dealt to a Demon creature you control of your choice.

Trample, haste
Whenever Lisseria, General of Kanaa attacks, you may exchange its power with the power of target creature defending player controls until end of turn.

Whenever you gain life, put a +1/+1 counter on Listless Maneli.
Surpass {5}{W} ({5}{W}: Transform this creature. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

Whenever Little Kibo attacks, you may pay {W}{W}. If you do, transform it.

When Little Pig enters, if you control a land named Far-Off Lands, put two +1/+1 counters on it.

When this creature enters, create a Treasure token.
This creature gets +1/+1 for each different name among tokens you control.