The Pokemon Company says you'll be able to grab packs from Deluxe Pack ex until October 30th, at which point they'll be removed
But realistically, this could be an insane card if your goal is to play Lands Combo, especially now with cards like Nadu, Winged Wisdom that encourage you to play all of the mana dorks so that you can scale your board exponentially
Higure will quickly end the game once it gets going, but it does take some work to get off the ground
Why play by the rules when you can cheat big time
If Quicksilver is consistent, he fundamentally changes the tempo of the game turn one
He's useful for fishing the final puzzle pieces out of your deck that you need to close out a game, or simply adding more damage to your opponent's board