One nonArt Card and nonLand card of any rarity is traditional foil, the Land card is traditional foil in 21% of packs, and a foil-stamped Signature Art Card replaces the Art Card in 5% of Set Boosters
The card grading investment workflow is straightforward: source raw cards, submit to a grading company, wait for the return, and sell the graded product
Raths overlay is interfering with the ther itself. Illustrated by Michael Sutfin Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Legal Comp
He was disqualified from his first Commander game after he played his second copy of Goblins of the Flarg, and it's all been uphill from there
One route would pair it with cards like Lier, Disciple of the Drowned and Chimil, the Inner Sun to prevent your spells from getting countered