Maestroke the Symphony Djinn [AP03-EN002] Ultimate Rare Generation Force you can negate the activation

you can negate the activation of a Spell/Trap Card

You can only use this effect of "Darklord Nasten" once per turn

and replace this effect with that monster's original effects

by banishing Fusion Materials from your hand

Maestroke the Symphony Djinn [AP03-EN002] Ultimate Rare Generation Force you can negate the activationSet: Astral Pack 3 Card type: Xyz Effect Monster Rarity: Ultimate Rare Attack: 1800 Defense: 2300 2 Level 4 monsters. Once per turn: You can detach 1 Xyz Material from this card, then target 1 face up Attack Position monster your opponent controls; change it to face down Defense Position. If a "Djinn" Xyz Monster you control would be destroyed, you can detach 1 Xyz Material from that monster instead.