msem-instigator

Search your library for a basic Forest card, put it onto the battlefield tapped, then shuffle.
Dominance — If you control the creature with the greatest power or tied for the greatest power, also search your library for a basic non-Forest card, reveal it, put it into your hand, then shuffle.

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

Put two +1/+1 counters on target creature. You gain life equal to that creature's power.

Until end of turn, creatures you control get +1/+1 and gain trample and poisonous 1. (Whenever one of those creatures deals combat damage to a player, that player gets a poison counter.)

Up to two target creatures can't block this turn.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Whenever a nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of it except it is an enchantment. (It still has its abilities, but it's not a creature or other types.)

Target creature gets +X/+0 until end of turn, where X is the number of instant and sorcery cards in your graveyard.

Trample
Whenever Lava Hellions attacks, you may have it consume. If you do, it deals 2 damage to defending player. (To consume, sacrifice another creature or exile a creature card from your graveyard.)

Lava Plume deals 3 damage to any target.
At the beginning of each end step, if you have 5 or less life, you may pay {R} and exile Lava Plume from your graveyard. If you do, it deals 3 damage to any target.

Menace
Whenever you sacrifice an artifact or creature, Lava Scutterer deals 2 damage to any target.

Vanishing 1 (This creature enters with a time counter on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever a creature you control deals combat damage to a player, put a time counter on Lavacore Elemental.

{4}{R}, Sacrifice Lavahurler: It deals 5 damage to target player or planeswalker.

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

Whenever a player looks at one or more cards in your library or searches your library, Lavamind Elemental deals 2 damage to that player. (This includes you.)
At the beginning of your end step, look at the bottom card of your library. You may put it on top of your library.

{2}{R}, Sacrifice Lavaspark Igniter: It deals 2 damage to target creature.

Menace

{1}{R}: Lavatongue Lizard gets +1/+0 until end of turn.
Ferocious — Whenever Lavatongue Lizard attacks, if you control a creature with power 4 or greater, Lavatongue Lizard gains first strike until end of turn.

Lavatrailer enters tapped.
Whenever a creature attacks you, if Lavatrailer is tapped, Lavatrailer deals 1 damage to it.

Return any number of lands you control to their owner's hands. For each land returned this way, search your library for a land card, reveal it, then put it into your hand. Then shuffle.

Whenever a creature you control dies, you may pay {G}. If you do, draw a card.

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Whenever a Role becomes attached to Lead Athlete or you cast a spell that targets it, put a +1/+1 counter on Lead Athlete.

Attacking creatures get +2/+0 until end of turn. If you control a legendary creature, those creatures also gain first strike until end of turn.

Target creature you control gets +3/+3 and gains trample until end of turn. Other creatures you control gain trample until end of turn.

{T}: Add {G}.

Flash
When Leafdown Ambusher enters, create three colorless artifact tokens named Arrow. They have “{T}, Tap an untapped creature you control, Sacrifice this permanent: The tapped creature fights target creature you don't control. Activate only as a sorcery unless this permanent entered this turn.”