Hero's Downfall

Ritual Chamber

When you unlock this door, create a 6/6 black Demon creature token with flying.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Unholy Annex

At the beginning of your end step, draw a card. If you control a Demon, each opponent loses 2 life and you gain 2 life. Otherwise, you lose 2 life.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Unholy Annex // Ritual Chamber

Preacher of the Schism

Deathtouch
Whenever this creature attacks the player with the most life or tied for most life, create a 1/1 white Vampire creature token with lifelink.
Whenever this creature attacks while you have the most life or are tied for most life, you draw a card and you lose 1 life.

Long Goodbye

This spell can't be countered. (This includes by the ward ability.)
Destroy target creature or planeswalker with mana value 3 or less.

Unstoppable Slasher

Deathtouch
Whenever this creature deals combat damage to a player, they lose half their life, rounded up.
When this creature dies, if it had no counters on it, return it to the battlefield tapped under its owner's control with two stun counters on it.

Demon Wall

Defender
Menace (This creature can't be blocked except by two or more creatures.)
As long as this creature has a counter on it, it can attack as though it didn't have defender.
{5}{B}: Put two +1/+1 counters on this creature.

Swamp

Intimidation Tactics

Target opponent reveals their hand. You choose an artifact or creature card from it. Exile that card.
Cycling {3} ({3}, Discard this card: Draw a card.)

Soulstone Sanctuary

{T}: Add {C}.
{4}: This land becomes a 3/3 creature with vigilance and all creature types. It's still a land.

Gatekeeper of Malakir

Kicker {B} (You may pay an additional {B} as you cast this spell.)
When this creature enters, if it was kicked, target player sacrifices a creature of their choice.

Virus Beetle

When this creature enters, each opponent discards a card.

The Soul Stone

Indestructible
{T}: Add {B}.
{6}{B}, {T}, Exile a creature you control: Harness The Soul Stone. (Once harnessed, its ∞ ability is active.)
∞ — At the beginning of your upkeep, return target creature card from your graveyard to the battlefield.

Bloodletter of Aclazotz

Flying
If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

Deep-Cavern Bat

Flying, lifelink
When this creature enters, look at target opponent's hand. You may exile a nonland card from it until this creature leaves the battlefield.