So long as a card was printed at common at any point, it is legal in the format (excluding acorn-stamped, illegal, and banned cards)
Cleanse Is a Card Wizards of the Coast Wants to Erase The artwork for Cleanse isnt objectionable on the surface, as it shows a tornado destroying an army of monsters
at a more tenable power level can still serve the players who earnestly love playing this sort of deck, while reducing the footprint the deck has in the metagame, by virtue of it being far less consistent
image600838 187 KB It is by Akira Egawa who also does work in Pokemon so that was a cool connection to make
The counters are a common enough payoff to avoid super-niche status
The Blastoise is one of three such hybrid cards discovered since 2016, joined by a fourth hybrid card with a black border unearthed as part of an uncut sheet of Magic: The Gathering cards kept by a former Wizards of the Coast employee