msem-instigator

{3}{W}{W}, Exile Leonin Insurgent from your graveyard: Create two 2/2 white Cat Soldier creature tokens. Activate only as a sorcery.

Tribute 2 (As this creature enters, an opponent of your choice may put two +1/+1 counters on it.)
When Leonin Sandfighter enters, if tribute was paid, it gains first strike. Otherwise it gains double strike. (This effect lasts indefinitely.)

Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)
Whenever Leotau Rider encourages a creature, that creature gains trample until end of turn.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever a +1/+1 counter is put onto Lerithan Rebel, it deals 1 damage to any target.

Whenever Leyline Tracer attacks, exile the top card of your library. Until end of turn, you may play that card.
Ascend—{B}, Discard two cards. ({B}, Discard two cards: Exile this creature, then return it to the battlefield transformed. Ascend only as a sorcery.)

When Leyran Spellchainer enters, return target instant or sorcery card from your graveyard to your hand.
{2}{R}: Transform Leyran Spellchainer. Activate only if it's attacking.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Lifelink
When Leyran-Pack Outcast attacks, if it's alpha, each player sacrifices a creature.

Trample

Flying, lifelink
Liesa has haste as long as it was foreshadowed.
When Liesa dies, each opponent sacrifices a creature and loses 2 life.
Foreshadow {4}{W}{B} (You may cast this spell for its foreshadow cost. If you do, also trigger its “dies” abilities when it enters.)

Menace
Whenever Lieshi Pariah deals combat damage, you lose that much life unless it's in a pack. (Two or more creatures you control with equal power are in a pack.)

Whenever a +1/+1 counter is put on Lifeblood Leecher, target creature an opponent controls gets -1/-1 until end of turn.

{3}{G}: Put a +1/+1 counter on Lifecaller Dryad.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)

Haste
At the beginning of each end step, if Lightning Ox dealt damage this turn, sacrifice it.

Whenever another artifact you control enters, put a +1/+1 counter on Lightsteel Enforcer.

Lightwalker has flying as long as it has a +1/+1 counter on it.

You may have Ligneous Enormity assign its combat damage as though it weren't blocked.
Madness {3}{G}{G} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Flash
Whenever a creature you control deals combat damage to a player, create a Treasure token, then exile the top card of that player's library. You may play cards exiled this way for as long as they remain exiled.

Haste
Deploy 5 (As this enters, you may tap any number of other creatures you control with total power 5 or more.)
When Line Officer enters deployed, it deals 3 damage to each creature your opponents control.

Trample
Engage (This creature must be blocked each combat if able.)
When Lion's Vanguard enters, creatures you control get +3/+3 and gain trample and haste until end of turn.

When Lively Prop dies, look at the top three cards of your library. You may reveal a creature card from among them and put it into your hand. Put the rest into your graveyard.

Living Broadcast can't block.
Whenever you cast a spell from exile, you may return Living Broadcast from your graveyard to your hand.

{R}{G}, Reveal Living Supernova from your hand: Put a land card from your hand onto the battlefield tapped. Activate only as a sorcery.
Whenever Living Supernova or a land you control enters, exile the top two cards of your library. Until the end of your next turn, you may play those cards.