msem-instigator

Counter target spell that targets you or a permanent you control.
Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Creatures you control get +2/+2 until end of turn.
Leitmotif (If you cast this spell from your hand, exile it as it resolves. When you next cast a spell that shares a color with this card, you may cast this from exile without paying its mana cost.)

Create three 2/1 red and white Fox creature tokens.

Exile all creatures, then for each creature exiled this way, you may return it to the battlefield under its owner's control. For each creature you didn't return to the battlefield this way, its owner may search their library for a basic land card and put it onto the battlefield tapped. Each player that does shuffles.

When Legacy Warmask enters, return target creature card with mana value 2 or less from your graveyard to the battlefield, then attach Legacy Warmask to that creature.
Equipped creature gets +1/+1.
Equip {1}

Flash
Enchant creature
As Legacy of Northrime enters, choose a creature type.
Enchanted creature gets +1/+4 and is the chosen type in addition to its other types.

Search your library and/or graveyard for an enchantment card with mana value X, put it onto the battlefield, then shuffle. Shuffle Legendweaving into its owner's library. X can't be 0.

Enchant creature
Enchanted creature and all other creatures with the same name as that creature can't attack or block.

[+2]: Create two 0/0 colorless Reflection creature tokens.
[–2]: Distribute four +1/+1 counters among any number of target creatures you control. You may tap or untap each of those creatures.
[–7]: You get an emblem with “Creature tokens you control can't leave the battlefield.”

Equipped creature has double strike.
Whenever equipped creature attacks, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
Abilities of Idols you control that target equipped creature cost {1} less to activate.
Equip {2}{W}

Enchant creature
Enchanted creature gains +X/+X, where X is your life total.
When enchanted creature dies, shuffle Life's Will into its owner's library.

Whenever you cast a white spell, create a 1/1 white Nymph creature token.

Put a +1/+1 counter on target creature. That creature gains first strike until end of turn.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, you gain life equal to the greatest power among creatures you control.

Creatures you control get +1/+1 until end of turn. Enchantment creatures you control gain vigilance until end of turn.
Flashback {4}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Once each turn, when a permanent is exiled from the battlefield by a spell or ability you control, you may draw a card.

When Lock Away enters, exile target nonland permanent an opponent controls until Lock Away leaves the battlefield.

Whenever you draw a card, put a quest counter on Lockdown.
As long as there are three or more quest counters on Lockdown, creatures with power 3 or greater don't untap during their controller's untap steps.

When Long Journey enters, exile target creature or planeswalker an opponent controls until Long Journey leaves the battlefield.

Exile up to one target creature or planeswalker. Its controller gains life equal to its mana value.
Orchestrate {W} (You may exile this card from your hand any time you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Tap target creature. Prevent all damage that would be dealt to and dealt by that creature this turn.

Exile target nonland permanent.

Target creature gets +2/+2 until end of turn. Untap it.

Creatures can't attack you or planeswalkers you control unless their controller pays 2 life for each of those creatures.

Creatures you control gain lifelink until end of turn.

Create a 1/1 white Bird creature token with flying. (Then exile this card. You may cast the creature later from exile.)