You can obtain the Rowlet (1-Diamond rarity) card by opening Celestial Guardians: Solgaleo from Celestial Guardians set
Im almost as big a fan of Anti-Venoms revival ability as I am of his durability, though, as its a great way to stabilize turn five in a monowhite deck
Secondly, and more broadly: in an 'unknown' environment, particularly a post-large-set new environment, new decks are generally likely to do better than established decks, because it's much easier for the new decks to prepare for an established metagame than for the established decks to figure out which of the new decks are most critical to adapt to
Decks that want to draw cards with Fact or Fiction are very unlikely to also be able to optimally use a Skullclamp, decks that have the mana to bust out a five or more mana draw spell are similarly unlikely to also want to use the economic but slow Ancestral Visions
Of course, it's hard to imagine a Charizard card would stay cheap forever, especially paired with a likable trainer, like Leon