This is thanks to Magic being home to a number of so-called "infinite" combos, which allow players to perform an action repeatedly until they win the game
UPDATE: According to two eBay "sold" listings, the Cosmic Foil Soul Stone card has sold for a whopping $15,000
#4 Sol Ring Turn 1 Sol Ring is one of the best starts in oldschool (or any format where it is legal), and the advantage of four mana available turn two should be self evident
Cards like Aura Shards and Fact or Fiction are strong but not exactly broken
Like cycling and the other cycling variants, the key to designing this mechanic is making sure that you want to trade in the card some of the time, which often means that the cards with transmute are more situational
It'll trigger Bess on arrival but won't be pumped by her when you swing with Bess so there's no reason to keep it loose and free