Seething Song

Sacrifice

As an additional cost to cast this spell, sacrifice a creature.
Add an amount of {B} equal to the sacrificed creature's mana value.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Thundermaw Hellkite

Flying
Haste (This creature can attack and {T} as soon as it comes under your control.)
When Thundermaw Hellkite enters, it deals 1 damage to each creature with flying your opponents control. Tap those creatures.

Stomping Ground

({T}: Add {R} or {G}.)
As Stomping Ground enters, you may pay 2 life. If you don't, it enters tapped.

Manamorphose

Add two mana in any combination of colors.
Draw a card.

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Sol Ring

Rite of Flame

Add {R}{R}, then add {R} for each card named Rite of Flame in each graveyard.

Talisman of Resilience

{T}: Add {C}.
{T}: Add {B} or {G}. Talisman of Resilience deals 1 damage to you.

Rakdos Signet

Swamp

Gamble

Search your library for a card, put that card into your hand, discard a card at random, then shuffle.

Spawn of Thraxes

Flying
When Spawn of Thraxes enters, it deals damage to any target equal to the number of Mountains you control.

Mana Geyser

Add {R} for each tapped land your opponents control.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: Aetherflux Reservoir deals 50 damage to any target.

Lathliss, Dragon Queen

Flying
Whenever another nontoken Dragon you control enters, create a 5/5 red Dragon creature token with flying.
{1}{R}: Dragons you control get +1/+0 until end of turn.

Utvara Hellkite

Flying
Whenever a Dragon you control attacks, create a 6/6 red Dragon creature token with flying.

Skithiryx, the Blight Dragon

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{B}: Skithiryx, the Blight Dragon gains haste until end of turn.
{B}{B}: Regenerate Skithiryx.

Prossh, Skyraider of Kher

When you cast this spell, create X 0/1 red Kobold creature tokens named Kobolds of Kher Keep, where X is the amount of mana spent to cast it.
Flying
Sacrifice another creature: Prossh, Skyraider of Kher gets +1/+0 until end of turn.

Mizzix's Mastery

Exile target card that's an instant or sorcery from your graveyard. For each card exiled this way, copy it, and you may cast the copy without paying its mana cost. Exile Mizzix's Mastery.
Overload {5}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Woodland Cemetery

Woodland Cemetery enters tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Geosurge

Add {R}{R}{R}{R}{R}{R}{R}. Spend this mana only to cast artifact or creature spells.

Diabolic Intent

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a card, put that card into your hand, then shuffle.

Snuff Out

If you control a Swamp, you may pay 4 life rather than pay this spell's mana cost.
Destroy target nonblack creature. It can't be regenerated.

Grapeshot

Grapeshot deals 1 damage to any target.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Llanowar Wastes

{T}: Add {C}.
{T}: Add {B} or {G}. Llanowar Wastes deals 1 damage to you.

Karplusan Forest

{T}: Add {C}.
{T}: Add {R} or {G}. Karplusan Forest deals 1 damage to you.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Allure of the Unknown

Reveal the top six cards of your library. An opponent exiles a nonland card from among them, then you put the rest into your hand. That opponent may cast the exiled card without paying its mana cost.

Bogardan Hellkite

Flash
Flying
When Bogardan Hellkite enters, it deals 5 damage divided as you choose among any number of targets.

Forest

Thunder Dragon

Flying
When Thunder Dragon enters, it deals 3 damage to each creature without flying.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Dragonskull Summit

Dragonskull Summit enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Spire Garden

Spire Garden enters tapped unless you have two or more opponents.
{T}: Add {R} or {G}.

Seismic Spike

Luxury Suite

Luxury Suite enters tapped unless you have two or more opponents.
{T}: Add {B} or {R}.

Arcane Signet

Overgrown Tomb

({T}: Add {B} or {G}.)
As Overgrown Tomb enters, you may pay 2 life. If you don't, it enters tapped.

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. Talisman of Indulgence deals 1 damage to you.

Scourge of Valkas

Flying
Whenever Scourge of Valkas or another Dragon you control enters, it deals X damage to any target, where X is the number of Dragons you control.
{R}: Scourge of Valkas gets +1/+0 until end of turn.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Dark Petition

Search your library for a card, put that card into your hand, then shuffle.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, add {B}{B}{B}.

Mogg Salvage

If an opponent controls an Island and you control a Mountain, you may cast this spell without paying its mana cost.
Destroy target artifact.

Demanding Dragon

Flying
When Demanding Dragon enters, it deals 5 damage to target opponent unless that player sacrifices a creature of their choice.

Skyline Despot

Flying
When Skyline Despot enters, you become the monarch.
At the beginning of your upkeep, if you're the monarch, create a 5/5 red Dragon creature token with flying.

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Rishkar's Expertise

Draw cards equal to the greatest power among creatures you control.
You may cast a spell with mana value 5 or less from your hand without paying its mana cost.

Firewild Borderpost

You may pay {1} and return a basic land you control to its owner's hand rather than pay this spell's mana cost.
Firewild Borderpost enters tapped.
{T}: Add {R} or {G}.

Knollspine Dragon

Flying
When Knollspine Dragon enters, you may discard your hand and draw cards equal to the damage dealt to target opponent this turn.

Pyretic Ritual

Burnt Offering

As an additional cost to cast this spell, sacrifice a creature.
Add X mana in any combination of {B} and/or {R}, where X is the sacrificed creature's mana value.

Ignite Memories

Target player reveals a card at random from their hand. Ignite Memories deals damage to that player equal to that card's mana value.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Brass's Bounty

For each land you control, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Culling the Weak

As an additional cost to cast this spell, sacrifice a creature.
Add {B}{B}{B}{B}.

Fireblast

You may sacrifice two Mountains rather than pay this spell's mana cost.
Fireblast deals 4 damage to any target.

Opportunistic Dragon

Flying
When Opportunistic Dragon enters, choose target Human or artifact an opponent controls. For as long as Opportunistic Dragon remains on the battlefield, gain control of that permanent, it loses all abilities, and it can't attack or block.

Liturgy of Blood

Blood Crypt

({T}: Add {B} or {R}.)
As Blood Crypt enters, you may pay 2 life. If you don't, it enters tapped.

Dark Ritual

Golgari Signet

Talisman of Impulse

{T}: Add {C}.
{T}: Add {R} or {G}. Talisman of Impulse deals 1 damage to you.

Dragonstorm

Search your library for a Dragon permanent card, put it onto the battlefield, then shuffle.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Mountain

Veinfire Borderpost

You may pay {1} and return a basic land you control to its owner's hand rather than pay this spell's mana cost.
Veinfire Borderpost enters tapped.
{T}: Add {B} or {R}.

Rootbound Crag

Rootbound Crag enters tapped unless you control a Mountain or a Forest.
{T}: Add {R} or {G}.

Foe-Razer Regent

Flying
When Foe-Razer Regent enters, you may have it fight target creature you don't control.
Whenever a creature you control fights, put two +1/+1 counters on it at the beginning of the next end step.

Sensei's Divining Top

{1}: Look at the top three cards of your library, then put them back in any order.
{T}: Draw a card, then put Sensei's Divining Top on top of its owner's library.

Sprouting Vines

Search your library for a basic land card, reveal that card, put it into your hand, then shuffle.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Lava-Field Overlord

Assist (Another player can pay up to {7} of this spell's cost.)
Flying
When Lava-Field Overlord enters, it deals 4 damage to target creature an opponent controls.

Boltwing Marauder

Flying
Whenever another creature you control enters, target creature gets +2/+0 until end of turn.

Tendrils of Agony

Target player loses 2 life and you gain 2 life.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

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.

Gruul Signet

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Infernal Plunge

As an additional cost to cast this spell, sacrifice a creature.
Add {R}{R}{R}.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Sunbird's Invocation

Whenever you cast a spell from your hand, reveal the top X cards of your library, where X is that spell's mana value. You may cast a spell with mana value X or less from among cards revealed this way without paying its mana cost. Put the rest on the bottom of your library in a random order.

Terror of Mount Velus

Flying
Double strike (This creature deals both first-strike and regular combat damage.)
When this creature enters, creatures you control gain double strike until end of turn.