Tergrid's Lantern

{T}: Target player loses 3 life unless they sacrifice a nonland permanent or discard a card.
{3}{B}: Untap Tergrid's Lantern.

Tergrid, God of Fright

Menace
Whenever an opponent sacrifices a nontoken permanent or discards a permanent card, you may put that card from a graveyard onto the battlefield under your control.

Tergrid, God of Fright // Tergrid's Lantern

Eaten by Piranhas

Flash
Enchant creature
Enchanted creature loses all abilities and is a black Skeleton creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Composer of Spring

Constellation — Whenever an enchantment you control enters, you may put a land card from your hand onto the battlefield tapped. If you control six or more enchantments, instead you may put a creature or land card from your hand onto the battlefield tapped.

Temple of the Dead

(Transforms from Aclazotz, Deepest Betrayal.)
{T}: Add {B}.
{2}{B}, {T}: Transform Temple of the Dead. Activate only if a player has one or fewer cards in hand and only as a sorcery.

Aclazotz, Deepest Betrayal

Flying, lifelink
Whenever Aclazotz attacks, each opponent discards a card. For each opponent who can't, you draw a card.
Whenever an opponent discards a land card, create a 1/1 black Bat creature token with flying.
When Aclazotz dies, return it to the battlefield tapped and transformed under its owner's control.

Aclazotz, Deepest Betrayal // Temple of the Dead

Starfield Mystic

Enchantment spells you cast cost {1} less to cast.
Whenever an enchantment you control is put into a graveyard from the battlefield, put a +1/+1 counter on Starfield Mystic.

Bolas's Citadel

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.
{T}, Sacrifice ten nonland permanents: Each opponent loses 10 life.

Heliod, the Warped Eclipse

You may cast spells as though they had flash.
Spells you cast cost {1} less to cast for each card your opponents have drawn this turn.

Heliod, the Radiant Dawn

When Heliod, the Radiant Dawn enters, return target enchantment card that isn't a God from your graveyard to your hand.
{3}{U/P}: Transform Heliod, the Radiant Dawn. Activate only as a sorcery. ({U/P} can be paid with either {U} or 2 life.)

Heliod, the Radiant Dawn // Heliod, the Warped Eclipse

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, 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

Jukai Naturalist

Lifelink
Enchantment spells you cast cost {1} less to cast.

Liliana's Scrounger

At the beginning of each end step, if a creature died this turn, you may put a loyalty counter on a Liliana planeswalker you control.

Chain of Smog

Target player discards two cards. That player may copy this spell and may choose a new target for that copy.