One way to do this is to examine the printing quality and texture of the card
Structure Deck: Soulburner contains a 40-card Main Deck + 6-card Extra Deck for a total of 46 cards: 39 Commons 4 Super Rares 3 Ultra Rares 1 Beginners Guide 1 Double-sided Deluxe Game Mat/Dueling Guide
YouTuber Tricky Gym explains that with the right drawing engines, this attack can be easily relied upon to take down the biggest of big Pokmon, and with Blacephalon coming from a meta dominated by bulky Fusions and VMAXs, that is hugely important
At the time, the movie was the highest-earning Japanese film to ever hit US cinemas
"Mushroom Man" appears in the post-Duel Slots if it was in the opponent's Graveyard, or if it was the opponent's Deck Leader
This way to chain spells in between turns and dig for cheap resources like Lotus Petal was the main reason why it was eventually banned in Pauper, despite not being dominant at the time it happened