pokemon toxicroak card 36/123 - Mysterious Treasures If heads Toxicroak | Black & White—Legendary

(As an aside - Appetite for Brains is probably my vote for the most overtly scary or graphic piece of MTG card art, but well explore other examples in more detail later)

As far as the rest of the deck, there will need to be tuning

Friede gaining control of Charizard in this state could be like Ash with his Lycanroc or Korrina with her Mega Lucario

Forcing your opponent's Sol Ring to enter tapped, or Mimic Vat, or whatever else they're casting is a huge tempo loss for them

Both are solid ways to take advantage of this, especially since Faldorn can exile cards itself to start feeding the pack

He did always have a habit of disappearing at key moments, but we can get around this with a blink spell to return him to the battlefield