msem-instigator

Enchant land
Enchanted land loses all land types, has “{T}: Add {C}”, and loses all other abilities.

Prowess
When Arcane Dredger enters, return target instant or sorcery card from your graveyard to your hand.

Each opponent sacrifices a creature. Whenever one or more players lose life this turn, repeat that process.

Whenever The Pyleas, Siona's Pride enters or attacks, look at the top six cards of your library. You may reveal a legendary non-Vehicle card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Crew 2

Flying, haste
Whenever you attack with three or more creatures, harmonize three times. (To harmonize, trigger up to one harmony of a permanent you control.)
If you would harmonize, you may instead return Herald of Festivities from your graveyard to your hand.

Shuffle a card from your hand into your library, then draw two cards.

When The Marrow Lord enters, search your library for a card with arise, put that card into your graveyard, then shuffle.
Whenever you activate an ability of a card in your graveyard or a creature you control enters from a graveyard, this creature deals 1 damage to any target.

Flying
{2/U}{2/U}: Exile Aeriform Remnant. Return it to the battlefield under its owner's control at the beginning of the next end step.

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever a creature you control enters, add a quest counter.
1 — You gain 3 life.
2 — Search your library for an Equipment card, reveal it, and put it into your hand. Then shuffle.
3 — You may put an Equipment card from your hand onto the battlefield and attach it to a creature you control.

Creatures you control gain vigilance until end of turn. After this main phase, there's an additional combat phase followed by an additional main phase.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

This spell can't be countered.
Flying
When Aunor, Dragonsire or another Dragon you control enters, untap target land. That land becomes a 5/5 Dragon creature with flying and haste in addition to its other types.

As this permanent transforms into Ameret, Shining and Proud, counters on them become loyalty counters instead.
[+1]: Until end of turn, you may have Ameret become an X/X Angel creature with flying, indestructible, and haste, where X is the number of counters on them.
[–2]: Create three 1/1 red and white Cleric creature tokens with lifelink and haste.

Vigilance
When this creature enters, you gain life equal to the greatest toughness among other creatures you control.

Flash
When Caronas, Eon Wanderer enters, you gain 2 life and draw two cards if Caronas, Eon Wanderer isn't on the battlefield.
{2}{W}{U}, Discard two cards: Aetherize Caronas. (To aetherize, create a token that's a copy of it, then exile that token.)

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)
Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)

Destroy target creature with no counters on it and no permanents attached to it.

Sunburst (This enters with a +1/+1 counter on it for each color of mana spent to cast it.)
Sacrifice another artifact: Put a +1/+1 counter on Plasma Enforcer.
When Plasma Enforcer dies, create a 1/1 colorless Servo artifact creature token for each +1/+1 counter on Plasma Enforcer.

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.)

{T}: Add {C}.
{T}: Add one mana of any color. Activate only if you have a counter.

Vigilance
Whenever Glittering Narwhal is dealt damage, create a Treasure token. (It's an artifact with “{T}, Sacrifice this permanent: Add one mana of any color.”)

Choose target creature or planeswalker. Its controller may exile it. If that player doesn't, they sacrifice all other creatures and planeswalkers they control.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Abandon Life and Hope deals 5 damage to target creature or planeswalker.

{2}{B}, Sacrifice a Clue: Target creature gets -3/-3 until end of turn.

(Add a quest counter as this enters. Sacrifice after 3.)
1, 2 — Whenever you attack with one or more creatures with power 4 or greater, add a quest counter.
3 — Until end of turn, target creature you control gains trample and “Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.”
Put two +1/+1 counters on target creature you control. It fights up to one target creature you don't control.