Fireslinger

{T}: This creature deals 1 damage to any target and 1 damage to you.

Barbarian Ring

{T}: Add {R}. This land deals 1 damage to you.
Threshold — {R}, {T}, Sacrifice this land: It deals 2 damage to any target. Activate only if seven or more cards are in your graveyard.

Roiling Vortex

At the beginning of each player's upkeep, this enchantment deals 1 damage to them.
Whenever a player casts a spell, if no mana was spent to cast that spell, this enchantment deals 5 damage to that player.
{R}: Your opponents can't gain life this turn.

Heartless Hidetsugu

{T}: Heartless Hidetsugu deals damage to each player equal to half that player's life total, rounded down.

Stuffy Doll

Indestructible
As this creature enters, choose a player.
Whenever this creature is dealt damage, it deals that much damage to the chosen player.
{T}: This creature deals 1 damage to itself.

Fire Diamond

This artifact enters tapped.
{T}: Add {R}.

Loxodon Warhammer

Equipped creature gets +3/+0 and has trample and lifelink.
Equip {3}

Basilisk Collar

Equipped creature has deathtouch and lifelink. (Any amount of damage it deals to a creature is enough to destroy it. Damage dealt by this creature also causes you to gain that much life.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Orcish Artillery

{T}: This creature deals 2 damage to any target and 3 damage to you.

Bolt Bend

This spell costs {3} less to cast if you control a creature with power 4 or greater.
Change the target of target spell or ability with a single target.

Earthquake

Earthquake deals X damage to each creature without flying and each player.

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 token: Add one mana of any color.")

Demand Answers

As an additional cost to cast this spell, sacrifice an artifact or discard a card.
Draw two cards.

Flame Rift

Flame Rift deals 4 damage to each player.

Ruby Medallion

Red spells you cast cost {1} less to cast.

Witch's Clinic

{T}: Add {C}.
{2}, {T}: Target commander gains lifelink until end of turn.

Auntie Blyte, Bad Influence

Flying
Whenever a source you control deals damage to you, put that many +1/+1 counters on Auntie Blyte.
{1}{R}, {T}, Remove X +1/+1 counters from Auntie Blyte: It deals X damage to any target.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Kediss, Emberclaw Familiar

Whenever a commander you control deals combat damage to an opponent, it deals that much damage to each other opponent.
Partner (You can have two commanders if both have partner.)

Sol Ring

Fortune Thief

Damage that would reduce your life total to less than 1 reduces it to 1 instead.
Morph {R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Arcane Signet

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

Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

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.)

Descent into Avernus

At the beginning of your upkeep, put two descent counters on this enchantment. Then each player creates X Treasure tokens and this enchantment deals X damage to each player, where X is the number of descent counters on this enchantment.

Goblin Artillery

Spear Spewer

Defender
{T}: This creature deals 1 damage to each player.

Blasphemous Act

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

Volcano Hellion

This creature has echo {X}, where X is your life total. (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When this creature enters, it deals an amount of damage of your choice to you and target creature. The damage can't be prevented.