The True Scriptures

(As this Saga enters and after your draw step, add a lore counter.)
I — For each opponent, destroy up to one target creature or planeswalker that player controls.
II — Each opponent discards three cards, then mills three cards.
III — Put all creature cards from all graveyards onto the battlefield under your control. Exile The True Scriptures, then return it to the battlefield (front face up).

Sheoldred

Menace
When Sheoldred enters the battlefield, each opponent sacrifices a nontoken creature or planeswalker.
{4}{B}: Exile Sheoldred, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery and only if an opponent has eight or more cards in their graveyard.

Sheoldred // The True Scriptures

Sidisi, Brood Tyrant

Whenever Sidisi, Brood Tyrant enters the battlefield or attacks, mill three cards.
Whenever one or more creature cards are put into your graveyard from your library, create a 2/2 black Zombie creature token.

Secrets of the Dead

Whenever you cast a spell from your graveyard, draw a card.

Perpetual Timepiece

{T}: Mill two cards.
{2}, Exile Perpetual Timepiece: Shuffle any number of target cards from your graveyard into your library.

Underrealm Lich

If you would draw a card, instead look at the top three cards of your library, then put one into your hand and the rest into your graveyard.
Pay 4 life: Underrealm Lich gains indestructible until end of turn. Tap it.

Lazotep Convert

You may have Lazotep Convert enter the battlefield as a copy of any creature card in a graveyard, except it's a 4/4 black Zombie in addition to its other colors and types.

Invasion of Amonkhet

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of Amonkhet enters the battlefield, each player mills three cards, then each opponent discards a card and you draw a card. (To mill three cards, a player puts the top three cards of their library into their graveyard.)

Invasion of Amonkhet // Lazotep Convert

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

Wrenn and Realmbreaker

Lands you control have "{T}: Add one mana of any color."
+1: Up to one target land you control becomes a 3/3 Elemental creature with vigilance, hexproof, and haste until your next turn. It's still a land.
−2: Mill three cards. You may put a permanent card from among the milled cards into your hand.
−7: You get an emblem with "You may play lands and cast permanent spells from your graveyard."

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Stitcher's Supplier

When Stitcher's Supplier enters the battlefield or dies, mill three cards.

Nevinyrral's Disk

Nevinyrral's Disk enters the battlefield tapped.
{1}, {T}: Destroy all artifacts, creatures, and enchantments.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Gravebreaker Lamia

Lifelink
When Gravebreaker Lamia enters the battlefield, search your library for a card, put it into your graveyard, then shuffle.
Spells you cast from your graveyard cost {1} less to cast.

Mesmeric Orb

Whenever a permanent becomes untapped, that permanent's controller mills a card.