msem-instigator

Haste
When Magma Crawler enters, creatures you control with flash or haste get +1/+1 until end of turn.

Haste
When Magmatic Violator enters, target opponent sacrifices a creature.
At the beginning of the end step, sacrifice Magmatic Violator.

At the beginning of your upkeep, if five or more instant and/or sorcery cards are in your graveyard, return target instant or sorcery card at random from your graveyard to your hand.

If a red instant or sorcery spell you control or a red planeswalker you control would deal damage to a permanent or player, it deals that much damage plus 2 instead.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
When Mahara enters, if you cast them, destroy all other creatures.
{W}{B}: Angel — You gain 4 life and amass Soldiers 4. (Put four +1/+1 counters on an Army you control. It's also a Soldier. If you don't control one, create an 0/0 black Soldier Army creature token first.)
{5}{W}{B}: Elder — Amass Soldiers 20.

Indestructible
Whenever this creature enters or transforms into Mahara, recruit. (Create a 0/0 white Soldier Army creature token, then put a +1/+1 counter on each Army you control.)
At the beginning of your end step, if you control four or more creatures, transform Mahara.

Flying
Whenever a permanent you control is returned to your hand, scry 1.

Majestic Nauticorn has first strike as long as it's attacking.
Cycling {W} ({W}, Discard this card: Draw a card.)

Menace, haste
Whenever Manic River-Fishers attacks, you may search defending player's library for an instant or sorcery card that shares a name with a card in their graveyard and cast it without paying its mana cost. That player shuffles.

When Marionette Phantom enters, choose one —
• Draw a card.
• Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

{1}{G}: Marrow Gorger must be blocked this turn if able.

Flying
When Marshcroaker Drake enters, you may return target creature with power 2 or less to its owner's hand.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
Vigilance
Martoob of Flowing Life has ward {X}, where X is the number of counters on her.
{G}{U}: Angel — Put a +1/+1 counter on each other creature you control.
{2}{G}{U}: Elder — Double the number of counters on permanents you control.

Menace
Whenever Masoh enters or attacks, each opponent that has more than four cards in hand discards cards equal to the difference. Then if you have fewer than four cards in hand, draw cards equal to the difference.

Flying
Whenever you cast an instant or sorcery spell from your hand, you may cast an instant or sorcery card with mana value less than or equal to that spell's mana value from your graveyard without paying its mana cost. Exile that card instead of putting it into your graveyard as it resolves.

Menace
Landfall — Whenever a land you control enters, Mawdryk's Elite gets +1/+0 and gains deathtouch until end of turn.

Whenever Mawdryk, Endrison Warden or another nontoken Elf creature you control enters, create a 1/1 green Elf Druid creature token.
{B}{G}, Sacrifice two Elves: Destroy target non-Elf creature.

Indestructible (Damage and effects that say “destroy” don't destroy this creature.)

When Mechanical Mastodon enters, you may return another target permanent you control to its owner's hand.

Colossal 4—{5}{U}{U}{U} (You may cast this for its colossal cost to have it enter with four +1/+1 counters; or pay {5}{U}{U}{U} as a sorcery: Put four +1/+1 counters on it if it has none.)
Whenever Megalokraken enters or attacks, reveal the top X cards of your library, where X is Megalokraken's power. You may cast a noncreature spell with mana value X or less from among them without paying its mana cost. Put the rest on the bottom of your library in a random order.

Meletian Trireme can't be blocked by creatures with power 2 or less.
Whenever Meletian Trireme enters or deals combat damage to a player or planeswalker, scry 1, then draw a card.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Lifelink
If a source would deal damage to a player, you may prevent X of that damage, where X is the number of +1/+1 counters on Mending Caretaker.

Other Elementals you control get +2/+2.
Whenever one or more Elementals you control attack, tap up to one target creature you don't control.

Menace

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
{2}{B}, Discard a card: Mercenary of the Folded Fan gains indestructible until end of turn. Tap it. If you're in a renaissance, draw a card.