Creature-based decks can get a lot from Thorn of Amethyst, but any deck capable of cheating these out and counteracting them with mana acceleration or a similar perk can wreck their opponents plans
We'll have to watch closely to see how things unfold
This page also includes advice to sell Magic: The Gathering cards UK players can use today
These cards are hard stax pieces, like Armageddon (lands), Jin-Gitaxias, Core Augur (hands), Hall of Gemstone (two or more mana colors), Iona, Shield of Emeria (spells of a specific color) Stasis (untap step) and Blood Moon (color fixing from nonbasics) all jump the fence and land squarely in the realm of shutting off decks either entirely or in part, keeping people from playing the game almost at all on their own once online depending on the meta
And a few extra turns to set up
They arent auras, or creatures you control, or even separate permanents attached to the top one