Trance Kuja, Fate Defied

Flare Star — If a Wizard you control would deal damage to a permanent or player, it deals double that damage instead.

Kuja, Genome Sorcerer

At the beginning of your end step, create a tapped 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent." Then if you control four or more Wizards, transform Kuja.

Kuja, Genome Sorcerer // Trance Kuja, Fate Defied

Dark Ritual

Swamp

Black Mage's Rod

Job select (When this Equipment enters, create a 1/1 colorless Hero creature token, then attach this to it.)
Equipped creature gets +1/+0, has "Whenever you cast a noncreature spell, this creature deals 1 damage to each opponent," and is a Wizard in addition to its other types.
Equip {3}

Black Waltz No. 3

Flying, deathtouch
Whenever you cast a noncreature spell, Black Waltz No. 3 deals 2 damage to each opponent.

Arcane Signet

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

Mountain

Cornered by Black Mages

Target opponent sacrifices a creature of their choice.
Create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent."

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.)

Fiery Emancipation

If a source you control would deal damage to a permanent or player, it deals triple that damage to that permanent or player instead.