msem-instigator

Whenever a creature you control enters for the first time each turn, you may sacrifice it. If you do, exile cards from the top of your library until you exile a creature card. Put that card onto the battlefield.

Frostpoint Caldera enters tapped unless you control a basic land.
{T}: Add {U} or {R}.

[+1]: Draw a card, then discard a card.
[–2]: Fulmen, Aether Prodigy deals 2 damage divided as you choose among one or two targets. Draw a card.
[–6]: Whenever you cast an instant or sorcery spell this turn, copy it. You may choose new targets for the copy.

{U}{R}, {T}: Fulmen deals 1 damage to target creature. When a creature dealt damage this way dies this turn, draw a card.
Whenever you cast an instant or sorcery spell, if you cast another instant or sorcery spell this turn, exile Fulmen, then return him to the battlefield transformed under his owner's control. He deals 3 damage to each creature.

[+2]: Draw two cards, then discard two cards unless you discard an instant or sorcery card.
[–3]: Reveal any number of cards from your hand. Fulmen deals damage to any target equal to the number of instant and sorcery cards revealed.
[–9]: Search each player's library for up to one instant card and one sorcery card. Cast those cards without paying their mana costs. Then each player shuffles.

Flying
Whenever you cast a creature spell, creatures you control get +1/+1 until end of turn.
Whenever you cast a noncreature spell, create a 2/2 red and white Cat Knight creature token.

At the beginning of your upkeep, mill two cards.
{1}{B}{B}: Until end of turn, Gaunt Abnormality becomes a copy of target creature card in your graveyard, except it's 3/3.

Whenever a creature you control enters, 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.”)
{2}, Sacrifice an Idol: Creatures you control get +1/+1 until end of turn.

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

When Gilded Authority enters, create two Treasure tokens. (They're artifacts with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Creatures your opponents control get -1/-0.

Flying
When Gilded Guardian dies, you may search your library for a legendary card, reveal it, put it into your hand, then shuffle.

Search your library for a planeswalker card, exile it with two loyalty counters on it, then shuffle. If that card has mana value 4 or less, you may activate one of its loyalty abilities. Then put that card into your hand.

Gloomtide Gulf enters tapped.
{T}: Add {U} or {B}.
{1}, {T}: Add one mana of any color.

Exile target creature you control, then return it to the battlefield under its owner's control.
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.”)

Attacking creatures you control have first strike.
Whenever three or more creatures you control die, Glorysinger deals 4 damage to any target.

Go Out Guns Blazing deals 2 damage to target player or planeswalker.
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.”)

Golden Company Valiant can block any number of creatures.
At the beginning of combat on each opponent's turn, Golden Company Valiant gets +1/+1 until end of turn for each creature that player controls.

Vigilance
Whenever the final chapter ability of a Saga you control resolves, you may return a non-Saga card at random from your graveyard to your hand.

This spell costs {1} less to cast for each counter on permanents you control.
Trample
{G}{G}, Remove ten counters from among permanents you control, Exile Grasp of the Stageless from your graveyard: Create a token that's a copy of Grasp of the Stageless. Activate only as a sorcery.

Whenever you attack, put a hatching counter on Greatwyrm's Egg. Then you may sacrifice it. If you do, create a tapped and attacking X/X red Dragon creature token with flying and haste, where X is the number of hatching counters on Greatwyrm's Egg.

Whenever Grin, Scourge of Goresand attacks, when you next cast an instant or sorcery spell with mana value 3 or less this turn, copy that spell. You may choose new targets for the copy.
Dash {2}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Target permanent gains hexproof and indestructible until end of turn. Scry 1.

Guidestone enters tapped.
{T}: Add {C}.
{2}, Sacrifice Guidestone: Draw a card.

Refine {3}{W}{B} (You may cast this spell by sacrificing an artifact and paying the refine cost reduced by that artifact's mana value.)
When H-9K Prototype enters, if it was refined, destroy target nonland permanent.

As Harlowe, Thespian Extraordinaire enters, choose a color and creature type.
Harlowe, Thespian Extraordinaire is the chosen color.
Harlowe, Thespian Extraordinaire is the chosen type in addition to its other types.