They also have, Whenever you cast a spell with X in its mana cost, create a 0/0 green Hydra creature token, then put X +1/+1 counters on it. That means that youll be generating an extra Hydra for nearly every Hydra you cast
The good thing is that you dont need to sort your bulk cards
While that's not the most terrible idea, the likelihood in a Niv-Mizzet deck is that the other spell you're casting is a burn spell that could do the same, and I have to feel that you're going to be better off casting it by itself, rather than putting all your eggs in one basket
While supporting local game stores is great, compare prices first, as some may resell retail-bought items
The most important thing to card game communities and the soon-to-be-millionaire who owns it, is that The One Ring was found in good condition, graded to ensure its quality, and now sits preserved in secure plastic casing