An Extra Monster Zone is not a part of either player's field until they Summon a monster to the Extra Monster Zone, meaning they are shared between the players
I think you're able to potentially win two copies of it too since the game rewards you for your wager like usual in addition to whatever card you get
Paying 6 mana for this fungus beast would be a fine rate and only requires gaining 3 life
Decks that are capable of cheating Summon: Bahamut into play in some capacity, like those built around Anikthea, Hand of Erebos, are elite homes for this card
But if you have a card that's faded almost completely, it's likely going to have a lower value than a card with its original colors
While losing ink from your inkwell may seem like a deficit, the cards are returned to your hand, giving you back some of the options you may have sacrificed in the early game to gain ink