There are some very rare test prints and reportedly some legitimate fillers that are blank foil, but I would steer clear of them unless you have rock solid provenance
Card Name Mana Cost Type Legendary Creature Human Noble Rarity Uncommon rules Text Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.) Whenever Queen Brahne attacks, create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent." P/T Number 149 Language English Legal Formats Alchemy, Brawl, Commander, Competitive Brawl, Historic, Legacy, Modern, Pioneer, Standard, Timeless, Vintage Rulings (6/6/2025) The Wizard token's ability resolves before the spell that caused it to trigger
Then I made the card legendary so that you could not have more than one in play at once
Some of the better early elf-decks rely on this sort of creature-based mana acceleration to win
Once you get these artifacts on the battlefield, they start to boost all your next moves, from creating huge tokens and doubling power to ramping and giving counters
But let's face it, we're playing Commander to cast giant monsters and huge spells because it's very hard to do that in formats where you don't have 40 life