Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Livaan, Cultist of Tiamat

Whenever you cast a noncreature spell, target creature gets +X/+0 until end of turn, where X is that spell's mana value.
Choose a Background (You can have a Background as a second commander.)

Harmonic Prodigy

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
If an ability of a Shaman or another Wizard you control triggers, that ability triggers an additional time.

Storm-Kiln Artist

Storm-Kiln Artist gets +1/+0 for each artifact you control.
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a Treasure token.

Twinning Staff

If you would copy a spell one or more times, instead copy it that many times plus an additional time. You may choose new targets for the additional copy.
{7}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

Arcane Signet

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

Dragon Fodder

Create two 1/1 red Goblin creature tokens.

Spikeshot Elder

{1}{R}{R}: Spikeshot Elder deals damage equal to its power to any target.

Vexing Shusher

This spell can't be countered.
{R/G}: Target spell can't be countered.

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Wort, the Raidmother

When Wort, the Raidmother enters, create two 1/1 red and green Goblin Warrior creature tokens.
Each red or green instant or sorcery spell you cast has conspire. (As you cast the spell, you may tap two untapped creatures you control that share a color with it. When you do, copy it and you may choose new targets for the copy.)

Sol Ring

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Kessig Flamebreather

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