msem-instigator

Prowess
Whenever you cast an instant or sorcery spell, if its mana value is less than or equal to Dwarven Twinslinger's power, copy that spell. You may choose new targets for the copy.

Counter target spell unless its controller pays {2}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Whenever Illumination Savant attacks, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Put a +1/+1 counter on each artifact creature and enchantment creature you control.

({T}: Add {B} or {R}.)
Whenever Crumbling Precipice becomes tapped, you lose 1 life unless you control two or more basic lands.

Enchant creature
Enchanted creature gets +1/+0 and has menace and “{1}{R}: This creature gets +1/+0 until end of turn.”

Choose a Function added to Rapid Recursion. Create a Function token with those effects. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)
Draw a card.

Target creature you control gets +2/+0 until end of turn. If that creature is attacking, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)

Harmony — You may pay {1}{G}. If you do, create a 3/3 green Beast creature token.
When Wildheart Chorister enters, harmonize. (Trigger up to one harmony of a permanent you control.)

Reverberate—Sacrifice a Swamp. (When you cast this spell, copy it if you paid its reverberate cost.)
All creatures get -2/-2 until end of turn.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
III — For each color, return up to one target creature card of that color from your graveyard to your hand.
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You may have Hero of Shengin Province assign its combat damage as though it weren't blocked.
{2}{G}: Until end of turn, you may have creatures you control assign combat damage as though they weren't blocked. Activate only if Hero of Shengin Province is in your graveyard.

Whenever Sirif of the Lord's Legion attacks, you may put a lore counter on target Saga you control.
Whenever Sirif deals combat damage to a player, you may remove a lore counter from target Saga you control.

Lifelink
When Disciple of the Coil enters, choose one —
• You draw a card and you lose 2 life.
• Put a +1/+1 counter on target creature you control.

Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)
When Aith Aera Sentinel enters, create a 1/1 green Elf creature token.

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Frontiers Anew {G}
Sorcery — Adventure
Search your library for a basic land card, reveal it, put it into your hand, then shuffle. (Then exile this card. You may cast the creature later from exile.)

Flash
When Stalker in the Mist enters, up to one target creature gets -1/-0 until end of turn.

Flying
Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast your second spell each turn, draw a card.

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
Whenever a creature you control blocks or becomes blocked, it gets +1/+1 until end of turn for each +1/+1 counter on it.

Flying, vigilance
At the beginning of your upkeep, if you have 10 or more life than your starting life total, put a +1/+1 counter on each other creature you control.

Flying
When Skymount Reinforcements enters, put a +1/+1 counter on another target creature.

{T}, Sacrifice Phosphorescent Ravine: Search your library for an Island or Swamp card and put it onto the battlefield tapped, then shuffle.

Draw two cards.
You may cast an instant or sorcery spell with mana value 3 or less from your hand or graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Landfall — This spell costs {2} less to cast if you had a land you control enter this turn.
Destroy target creature.

Flying
When Highspire Informant enters, scry 1.

Flash
Deathtouch