Card Rules: Rulings powered by The Netrep API. 'Metamorphosis' does not properly Summon a Fusion Monster, so you cannot use 'Monster Reborn' on it afterwards. Tributing a monster is a cost. You can Tribute a face-down monster. If you activated 'Soul Exchange' targeting your opponent's monster, if the monster is face-down, you cannot Tribute it as a cost for 'Metamorphosis'. You can Tribute a Monster Token (including a Sheep Token from 'Scapegoat'). If there is no Fusion Monster with the same level as the Tributed monster in your Extra Deck, then you cannot activate this card. 'Metamorphosis' vs. 'A Legendary Ocean': if you want to Special Summon a Level 6 Fusion Monster from your Extra Deck, you have to Tribute a Level 7 WATER monster on the field because it is treated as a Level 6. [Re: Chthonian Polymer] You can only activate this card when the opponent Fusion Summons a monster, including with a Special Summon that is treated as a Fusion Summon, like 'Miracle Fusion' or 'Power Bond'. You cannot activate it when they Special Summon a Fusion Monster with a card effect, like 'Metamorphosis' or 'Cyber-Stein'. [Re: Cyber End Dragon] You can Special Summon 'Cyber End Dragon' with 'Cyber-Stein' or 'Metamorphosis'. [Re: Cyber Twin Dragon] You can Special Summon 'Cyber Twin Dragon' with 'Cyber-Stein' or 'Metamorphosis'. [Re: De-Fusion] If you activate 'De-Fusion' and select a Fusion Monster that was Special Summoned by 'Magical Scientist' or 'Metamorphosis' you can return the Fusion Monster to the owner's Extra Deck, but cannot Special Summon any Fusion Material Monsters since none were used. [Re: Elemental Hero Necroid Shaman] You cannot choose to Special Summon a monster if it cannot be Special Summoned, such as a Spirit monster, or 'Dark Ruler Ha Des', or a Fusion Monster that was Summoned by the effect of 'Metamorphosis'. [Re: Fiend Skull Dragon] You cannot use substitute Fusion Material Monsters such as 'Beastking of the Swamps' to Fusion Summon this card. You can use the effects of 'Metamorphosis', 'Magical Scientist', and 'Summoner of Illusions' to Special Summon this card. [Re: Non-Fusion Area] You can still Special Summon a Fusion Monster with a card effect like 'Metamorphosis' or 'Cyber-Stein'. [Re: Serial Spell] If you chain 'Serial Spell' to 'Metamorphosis', there is no effect because you did not Tribute a monster for a cost, so 'Serial Spell' has no point of reference and cannot resolve. [Re: Soul Exchange] You can target a face-down monster, but you cannot Tribute it for a Ritual Summon or for 'Metamorphosis' because you do not know its Level. [Re: UFOroid Fighter] If 'UFOroid Fighter' is Special Summoned with 'Cyber-Stein' or 'Metamorphosis', its original ATK & DEF will be zero.