A captured elemental makes for a potent, albeit unstable, power source.

Storm-Kiln Artist

This creature gets +1/+0 for each artifact you control.
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

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.

The List

Secret Lair Drop

Secrets of Strixhaven Commander

Tarkir: Dragonstorm Commander

Outlaws of Thunder Junction Commander

Commander Masters

"First you summon the lightning, then you make it dance."