Must be either Fusion Summoned, or Special Summoned (from your Extra Deck) by discarding 1 Spell/Trap and Tributing 1 Level 7 or higher "Artmage" monster from your hand or field. You can only Special Summon "Artmage Non-Finito" once per turn this way, no matter which method you use. If this card is Special Summoned: You can Set 1 "Artmage" Spell/Trap from your Deck. Once per opponent's turn (Quick Effect): You can Fusion Summon 1 Fusion Monster from your Extra Deck using monsters you control.
