You can use the r/PokemonMisprints community to see if its an error or a fake, or go with CGC, one of the best Pokmon grading services for error cards
However, he is much more difficult than the other Behemoths because he will also blanket the battlefield with elemental magic
We've seen it before with almost every expansion, with players most recently predicting Espeon and Umbreon from Eevee Grove would spell the end for DarkTina, that the Ultra Beasts from Extradimensional Crisis would break the meta, and Celestial Guardians' Rare Candy would change things forever
Since the Deck can create a strong board from few cards in hand, it will often have cards spare and can afford to play many Spell/Trap Cards, potentially ones with discard costs such as "Constructor Ambush" or "Cranked to Ten!!" to make use of the extra cards
These anthems also really helped scale up Mausoleum Wanderer, frequently it was at 2 or 3 power thus making it a much harder disruptive tool