Brimstone Roundup

Whenever you cast your second spell each turn, create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."
Plot {2}{R} (You may pay {2}{R} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Swiftwater Cliffs

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {R}.

Negate

Frostboil Snarl

As Frostboil Snarl enters, you may reveal an Island or Mountain card from your hand. If you don't, Frostboil Snarl enters tapped.
{T}: Add {U} or {R}.

Into the Flood Maw

Gift a tapped Fish (You may promise an opponent a gift as you cast this spell. If you do, they create a tapped 1/1 blue Fish creature token before its other effects.)
Return target creature an opponent controls to its owner's hand. If the gift was promised, instead return target nonland permanent an opponent controls to its owner's hand.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Island

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Clockwork Percussionist

Haste
When Clockwork Percussionist dies, exile the top card of your library. You may play it until the end of your next turn.

Chainsaw

When Chainsaw enters, it deals 3 damage to up to one target creature.
Whenever one or more creatures die, put a rev counter on Chainsaw.
Equipped creature gets +X/+0, where X is the number of rev counters on Chainsaw.
Equip {3}

Essence Capture

Counter target creature spell. Put a +1/+1 counter on up to one target creature you control.

Kessig Flamebreather

Whenever you cast a noncreature spell, Kessig Flamebreather deals 1 damage to each opponent.

Fear, Fire, Foes!

Damage can't be prevented this turn. Fear, Fire, Foes! deals X damage to target creature and 1 damage to each other creature with the same controller.

Access Denied

Counter target spell. Create X 1/1 colorless Thopter artifact creature tokens with flying, where X is that spell's mana value.

Electrostatic Field

Defender
Whenever you cast an instant or sorcery spell, Electrostatic Field deals 1 damage to each opponent.

Kindlespark Duo

{T}: Kindlespark Duo deals 1 damage to target opponent.
Whenever you cast a noncreature spell, untap Kindlespark Duo.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Playful Shove

Playful Shove deals 1 damage to any target.
Draw a card.

Enduring Curiosity

Flash
Whenever a creature you control deals combat damage to a player, draw a card.
When Enduring Curiosity dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Stensia Uprising

At the beginning of your end step, create a 1/1 red Human creature token. Then if you control exactly thirteen permanents, you may sacrifice Stensia Uprising. When you do, it deals 7 damage to any target.

Eroded Canyon

Eroded Canyon enters tapped.
When Eroded Canyon enters, it deals 1 damage to target opponent.
{T}: Add {U} or {R}.

Thermo-Alchemist

Defender
{T}: Thermo-Alchemist deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

Shivan Gorge

{T}: Add {C}.
{2}{R}, {T}: Shivan Gorge deals 1 damage to each opponent.

Big Score

As an additional cost to cast this spell, discard a card.
Draw two cards and create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Inferno Titan

{R}: Inferno Titan gets +1/+0 until end of turn.
Whenever Inferno Titan enters or attacks, it deals 3 damage divided as you choose among one, two, or three targets.

Bjorna, Nightfall Alchemist

{T}, Sacrifice an artifact: Bjorna, Nightfall Alchemist deals 1 damage to target creature. Goad that creature. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)
Friends forever (You can have two commanders if both have friends forever.)

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Barbflare Gremlin

First strike, haste
Whenever a player taps a land for mana, if Barbflare Gremlin is tapped, that player adds one mana of any type that land produced. Then that land deals 1 damage to that player.

Mayhem Patrol

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Mayhem Patrol attacks, target creature gets +1/+0 until end of turn.
Blitz {1}{R} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

Dagger Caster

When Dagger Caster enters, it deals 1 damage to each opponent and 1 damage to each creature your opponents control.

Thriving Isle

Thriving Isle enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Sorcerer's Wand

Equipped creature has "{T}: This creature deals 1 damage to target player or planeswalker. If this creature is a Wizard, it deals 2 damage instead."
Equip {3}

Witty Roastmaster

Alliance — Whenever another creature you control enters, Witty Roastmaster deals 1 damage to each opponent.

Unruly Catapult

Defender
{T}: Unruly Catapult deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Unruly Catapult.

Spirebluff Canal

Spirebluff Canal enters tapped unless you control two or fewer other lands.
{T}: Add {U} or {R}.

Repulse

Return target creature to its owner's hand.
Draw a card.

Goblin Fireleaper

{1}{R}: Goblin Fireleaper gets +1/+0 until end of turn.
When Goblin Fireleaper dies, it deals damage equal to its power to target creature an opponent controls.

Compulsive Research

Target player draws three cards. Then that player discards two cards unless they discard a land card.

Falkenrath Perforator

Whenever Falkenrath Perforator attacks, it deals 1 damage to defending player.

Steampath Charger

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
When this creature dies, it deals 1 damage to target player.

Ghyrson Starn, Kelermorph

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Three Autostubs — Whenever another source you control deals exactly 1 damage to a permanent or player, Ghyrson Starn, Kelermorph deals 2 damage to that permanent or player.

Assassin Gauntlet

When Assassin Gauntlet enters, attach it to up to one target creature you control. Tap all creatures target opponent controls.
Equipped creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, draw a card, then discard a card."
Equip {2}

Arcane Signet

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

Izzet Guildgate

This land enters tapped.
{T}: Add {U} or {R}.

Run Away Together

Choose two target creatures controlled by different players. Return those creatures to their owners' hands.

Twist Reality

Choose one —
• Counter target spell.
• Manifest dread. (Look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)

Loyal Apprentice

Haste
Lieutenant — At the beginning of combat on your turn, if you control your commander, create a 1/1 colorless Thopter artifact creature token with flying. That token gains haste until end of turn.

Temple of Epiphany

This land enters tapped.
When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {U} or {R}.

Coruscation Mage

Offspring {2} (You may pay an additional {2} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Shattered Yard

At the beginning of your end step, this Room deals 1 damage to each opponent.
(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.)

Glassworks

When you unlock this door, this Room deals 4 damage to target creature an opponent controls.
(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.)

Glassworks // Shattered Yard

Highway Robbery

You may discard a card or sacrifice a land. If you do, draw two cards.
Plot {1}{R} (You may pay {1}{R} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Niv-Mizzet, Visionary

Flying
You have no maximum hand size.
Whenever a source you control deals noncombat damage to an opponent, you draw that many cards.

Firebrand Archer

Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Mountain

Glimmerburst

Draw two cards. Create a 1/1 white Glimmer enchantment creature token.

Shao Jun

Leap Strike — During your turn, Shao Jun has flying and first strike.
Rope Dart — Tap two untapped artifacts you control: Shao Jun deals 1 damage to each opponent.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Sol Ring

Volcanic Rambler

{2}{R}: Volcanic Rambler deals 1 damage to target player or planeswalker.

Erebor Flamesmith

Whenever you cast an instant or sorcery spell, Erebor Flamesmith deals 1 damage to each opponent.

Rampaging Ferocidon

Menace
Players can't gain life.
Whenever another creature enters, Rampaging Ferocidon deals 1 damage to that creature's controller.

Sleep

Tap all creatures target player controls. Those creatures don't untap during that player's next untap step.

Command Tower

Enter the Enigma

Target creature can't be blocked this turn.
Draw a card.

Razorkin Needlehead

Razorkin Needlehead has first strike during your turn.
Whenever an opponent draws a card, Razorkin Needlehead deals 1 damage to them.

End the Festivities

End the Festivities deals 1 damage to each opponent and each creature and planeswalker they control.

Rabbit Battery

Haste
Equipped creature gets +1/+1 and has haste.
Reconfigure {R} ({R}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Whispering Wizard

Whenever you cast a noncreature spell, create a 1/1 white Spirit creature token with flying. This ability triggers only once each turn.

Fishing Pole

Equipped creature has "{1}, {T}, Tap Fishing Pole: Put a bait counter on Fishing Pole."
Whenever equipped creature becomes untapped, remove a bait counter from this Equipment. If you do, create a 1/1 blue Fish creature token.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Geistflame

Geistflame deals 1 damage to any target.
Flashback {3}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Neonate's Rush

This spell costs {1} less to cast if you control a Vampire.
Neonate's Rush deals 1 damage to target creature and 1 damage to its controller. Draw a card.

Locker Room

Whenever one or more creatures you control deal combat damage to a player, draw a card.
(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.)

Bottomless Pool

When you unlock this door, return up to one target creature to its owner's hand.
(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.)

Bottomless Pool // Locker Room

Sunspine Lynx

Players can't gain life.
Damage can't be prevented.
When Sunspine Lynx enters, it deals damage to each player equal to the number of nonbasic lands that player controls.

Torture Pit

If a source you control would deal noncombat damage to an opponent, it deals that much damage plus 2 instead.
(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.)

Spiked Corridor

When you unlock this door, create three 1/1 red Devil creature tokens with "When this creature dies, it deals 1 damage to any target."
(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.)

Spiked Corridor // Torture Pit

Reckless Lackey

First strike, haste
{2}{R}, Sacrifice Reckless Lackey: Draw a card and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Obsessive Search

Draw a card.
Madness {U} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)