msem-instigator

When Lunar Vigil enters, draw a card, then scry 2.
If you would draw one or more cards, you may instead put a night counter on Lunar Vigil and draw that many cards minus one.
Sacrifice Lunar Vigil: Target player draws a card and adds {R} for each night counter on it.

When Lurking Angler enters, if seven or more cards are in your graveyard, draw a card. Otherwise, mill two cards.

First mate—Each nonland card in your starting deck is an instant or has flash. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Flash
When Mable enters, you gain 2 life and draw a card.

Flash (You may cast this spell any time you could cast an instant.)
When Majestic Hippocamp enters, target creature gets -2/-0 until end of turn.

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

Put any number of target creature cards from your graveyard on top of your library.
You draw two cards, and you lose 2 life.

Pressure {G} (You may cast this spell for its pressure cost if there are seven or more cards in your graveyard.)
Deathtouch

Marin Polgek, Academy Heiress has hexproof as long as you control three or more enchantments.
{1}{W/U}{W/U}: Create a token that's a copy of target enchantment you control.

First mate—Each nonland card in your starting deck has “destroy,” “die,” “graveyard,” and/or “mill” in its printed rules text. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Deathtouch
When Marisa enters, if it was cast, you may put target permanent card from a graveyard onto the battlefield under your control.

Enchant opponent
Whenever enchanted player searches their library, you may search your library for a card, put it into your hand, then shuffle.

Gain control of target creature until end of turn. Put a +1/+1 counter on it and untap it. That creature gains haste until end of turn.

As an additional cost to cast this spell, sacrifice a permanent.
Exile target creature.

Trample
Enchantment spells and Aurashaper spells you cast cost {1} less to cast.
Whenever another enchantment you control enters, draw a card.

At the beginning of combat on your turn, if you cast an enchantment spell, an instant spell, and a sorcery spell this turn, create two 3/3 red Shark enchantment creature tokens. You may have any number of those tokens gain haste. If you do, sacrifice the tokens you chose at end of combat.

[+2]: Each opponent loses 2 life. Scry 2.
[–3]: Return target creature to its owner's hand. That player discards a card.
[–6]: You get an emblem with “Whenever a player discards a card, you may cast it without paying its mana cost.”

Enchant opponent
Whenever a creature enters under enchanted player's control, that creature gets -0/-2 until end of turn unless that player pays 2 life.

Crew 3 (Tap any number of creatures you control with total power 3 or greater: This Vehicle becomes an artifact creature until end of turn.)

Whenever Merciless Bandit or another creature you control dies, each opponent loses 1 life and you gain 1 life.

Whenever Merrow Legendmaker attacks, look at the top five cards of your library. You may reveal an Aura, Aurashaper, or Equipment card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

When Mettalia's Forward enters, you may salvage a card. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

When Militant's Standard enters, draw a card if you control a Merfolk.
Equipped creature gets +2/+1.
Equip {2}

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
You may cast the first spell that's an enchantment, instant, or sorcery with mana value 1 you cast each turn without paying its mana cost.

When Mindbreak Artisan enters, you may search your library for an artifact card, reveal it, shuffle, then put that card on top.
Other artifacts you control have “You may choose not to untap this artifact during your untap step” and “{3}{U}{U}, {T}: Gain control of target creature for as long as you control this artifact and it remains tapped.”

{2}{R}, Sacrifice Minefield Bomber: It deals 2 damage to any target.
Cycling {2/R} ({2/R}, Discard this card: Draw a card.)

Mirrorgate enters tapped.
When Mirrorgate enters, you choose a nonbasic land card name other than Mirrorgate, then each player chooses a color.
Lands with the chosen name are lands with “{T}: Add one mana of any of the chosen colors,” and lose all other abilities, card types, and land types.
{T}: Add one mana of any of the chosen colors.