Apply this effect, depending on the Extra Deck monster card types (Fusion, Synchro, or Xyz) of monsters you control. You must control exactly 2 different monster card types to activate and to resolve this effect.
• Fusion and Synchro: Special Summon 1 "Outer Entity" Xyz Monster from your Extra Deck, and if you do, attach this card to it as Xyz Material.
• Synchro and Xyz: Special Summon 1 "Elder Entity" Fusion Monster from your Extra Deck.
• Xyz and Fusion: Special Summon 1 "Old Entity" Synchro Monster from your Extra Deck.
You can only activate 1 "Forbidden Trapezohedron" per turn.