msem-instigator

(Add a quest counter as this enters. Sacrifice after 3.)
Whenever you draw your second card each turn, add a quest counter.
Scry 3.
Create a blue and green enchantment token named The Heart with “Whenever you tap a land for mana, add one mana of any color.”

First strike
Whenever The Heart-hardened or another creature you control dies, each opponent loses 1 life. If this is the third time this ability has resolved this turn, you draw three cards and you lose 3 life.

Flash
Hexproof
{3}, Exile two cards from your graveyard: Gain control of target spell or permanent if it shares a type with both of those cards.

First strike, trample
Death knell — Return a permanent card with mana value less than X from your graveyard to the battlefield, where X is the mana value of the last creature that died this turn. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

When The Lonely Prophet enters, exile a card you own from outside the game face down.
Whenever The Lonely Prophet deals combat damage, put the exiled card into your hand.

Whenever you cast an enchantment spell, you may put target creature on the bottom of its owner's library.

Hexproof
Whenever an opponent casts a spell or draws a card, draw a card.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Return target creature card from your graveyard to your hand.
II — Return target instant or sorcery card from your graveyard to your hand.
III — At the beginning of the next end step, create an X/X black Horror creature token, where X is the number of spells you cast this turn.

Codex — Out-of-Body Experience; Event Horizon; Strike from the Shadows; Second Death; Anguished Unmaking. (As this enters, conjure its contents into a shuffled face-up additional library.)
You can't draw from this codex's library.
Whenever a creature you control dies, put a card from this codex's library into your hand.

The Mythical Zhiwu enters with four +1/+1 counters on it.
{1}, Remove a +1/+1 counter from a creature you control: Target creature gets -1/-1 until end of turn. Activate only as a sorcery.
{1}, Remove a +1/+1 counter from a creature you control: Each opponent loses 1 life and you gain 1 life.

The Oltenen Emissary is all colors.
You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells that you cast. When you do, you may cast spells without paying their mana costs until end of turn.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
Put a prowess counter on target creature you control. That creature deals 2 damage to each opponent.
Scry 3.
Until end of turn, if you casting an instant or sorcery spell causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Whenever The Pursuit of Science enters or a nontoken creature you control dies, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Clues you control have “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”

As an additional cost to cast this spell, you may tap any number of creatures you control. This spell costs {1} less to cast for each creature tapped in this way.
Create X 1/1 white Peasant creature tokens. You gain X life. Legendary creatures you control gain hexproof and indestructible until end of turn.

When The Raven Queen of Fretport enters, put a -1/-1 counter on each of any number of target creatures.
{2}{U}{B}: Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create two 1/1 colorless Construct Actor creature tokens.
II — Creatures you control gain first strike until end of turn.
III — Creatures you control get +1/+0 until end of turn.

(Choose only one work as a sorcery to add its ability.)
When The Royal Vignettes enters, exile target instant or sorcery card from your graveyard. Until your next turn, you may cast that card.
{1}{U}: Ju, the Artisan
Whenever you cast an instant spell, draw a card, then discard a card.
{1}{R}: Lan, the Poet
Whenever you cast a sorcery spell, create a 1/1 red Bard creature token with “This creature can't block.”

At the beginning of your end step, create a 1/1 colorless Human creature. Put a sacrifice counter on it.
Creature tokens you control with sacrifice counters on them can't attack or block and have “Sacrifice this creature: Add {C}.”

Trample
When The Shepherd of Nowhere enters, each player sacrifices each other nontoken creature they control.
Whenever another nontoken creature you control dies, create a token that's a copy of that creature.

At the beginning of your upkeep, you lose 1 life, then reveal the top card of your library. You lose life equal to its mana value unless it is a creature card. Put that card into your hand.

Primal {5}{W}{B} (During your turn, you may cast this spell for {5}{W}{B} instead of playing a land.)
Destroy all creatures. If this spell was cast for its primal cost, for each player, put up to one creature card from that player's graveyard onto the battlefield under your control.

At the beginning of each player's end step, that player chooses from among nonland permanents they control an artifact, a creature, an enchantment, and a planeswalker, then sacrifices the rest.

Deathtouch, lifelink
At the beginning of combat on your turn, for each creature your opponents control, you may tap an untapped creature you control. If you do, those creatures fight each other.

(Add a quest counter as this enters. Sacrifice after 3.)
At the beginning of your end step, if you cast two or more spells this turn, add a quest counter.
The Symphony of Leafdown deals 2 damage to any target. Draw a card.
Until the end of your next turn, instant and sorcery spells you cast cost {1} less to cast.

For each legendary permanent you control, this spell costs one mana of one of that permanent's colors less to cast. This effect reduces only the amount of colored mana you pay.
For each color, create a token that's a copy of a different legendary permanent you control of that color, except the token isn't legendary.
Exile The Tale of Kings.