Self-Destruct

Target creature you control deals X damage to any other target and X damage to itself, where X is its power.

Firebrand Archer

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

Screaming Nemesis

Haste
Whenever this creature is dealt damage, it deals that much damage to any other target. If a player is dealt damage this way, they can't gain life for the rest of the game.

Taii Wakeen, Perfect Shot

Whenever a source you control deals noncombat damage to a creature equal to that creature's toughness, draw a card.
{X}, {T}: If a source you control would deal noncombat damage to a permanent or player this turn, it deals that much damage plus X instead.

Firesong and Sunspeaker

Red instant and sorcery spells you control have lifelink.
Whenever a white instant or sorcery spell causes you to gain life, Firesong and Sunspeaker deals 3 damage to target creature or player.

Radiant Lotus

{T}, Sacrifice one or more artifacts: Choose a color. Target player adds three mana of the chosen color for each artifact sacrificed this way.

Molten Psyche

Each player shuffles the cards from their hand into their library, then draws that many cards.
Metalcraft — If you control three or more artifacts, Molten Psyche deals damage to each opponent equal to the number of cards that player has drawn this turn.

Arcane Signet

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

Razorkin Needlehead

This creature has first strike during your turn.
Whenever an opponent draws a card, this creature deals 1 damage to them.

Sol Ring

Goblin Bombardment

Sacrifice a creature: This enchantment deals 1 damage to any target.

Magda, the Hoardmaster

Whenever you commit a crime, create a tapped Treasure token. This ability triggers only once each turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)
Sacrifice three Treasures: Create a 4/4 red Scorpion Dragon creature token with flying and haste. Activate only as a sorcery.

Impact Tremors

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