Generation of Heroes

At the beginning of the Duel, add 15 "Elemental HERO" monsters to your Extra Deck. Also, the following effect can be used once per Duel if you control one of the following monsters. Set 1 "Skyscraper" to your field from outside of your Deck. This Skill can only be used/applied if you begin the Duel with a Deck (including Extra Deck) that contains at least 17 "Elemental HERO" monsters including all of the following monsters: ● "Wingman" Fusion Monster ● Elemental HERO Avian ● Elemental HERO Burstinatrix ● Elemental HERO Clayman ● Elemental HERO Sparkman ● Elemental HERO Bubbleman