Show: All formats Perfect Circle Edison
Because the Summon from “Instant Fusion” is a Fusion Summon, Fusion Monsters with the text "A Fusion Summon of this monster can only be conducted with the above Fusion Material Monsters.” cannot be Special Summoned with “Instant Fusion”.
If that monster becomes flipped face-down, the effects "Its effects are negated, also it is destroyed during each End Phase" are no longer applied to it.
Since the Special Summon from “Instant Fusion” is treated as a Fusion Summon, you can use “Premature Burial” etc. on the Fusion Monster if it is destroyed.
Even if “Non-Spellcasting Area” is active, a Fusion Monster that is not an Effect Monster (such as “Flame Swordsman”) will still be affected by the restrictions on “Instant Fusion”. So it still cannot attack and it is still destroyed at the end of this turn.
Even though only 1 copy of this card can be activated each turn, you can chain “Serial Spell” to it to duplicate the effect.
If “Destiny Hero – Diamond Dude” uses its effect and reveals “Instant Fusion”, you can still activate another “Instant Fusion” that same turn.