The Ring's emblem of temptation relies on players having good creatures that can attack effectively without being killed by blockers too easily, so the effect may be better used by creature-heavy decks that are already adept at pushing damage, or even control decks that can attack with a single, evasive creature to close out the game
Ancient Copper Dragon FINAL FANTASY: Through the Ages, Mythic Limited: 2.0 If you hit them with Dragon of Mount Gulg (Ancient Copper Dragon), this likely will win you the game, but thats true of most six-mana cards
It won't copy any other effects that have changed that creature's power, toughness, color, and so on
It would probably only find one creature (and might still have to cost 4G, or be a sorcery)
If you held this entire time, you just got 4 years of no returns
Learning new skills and coming to appreciate some of the game mechanics that are found in newer sets can be a lot of fun, but is also easily overlooked when a player already has that perfect winning deck that has never been beat