You can Special Summon this card (from your hand) by discarding 1 card. You can only Special Summon "Nightmare Apprentice" once per turn this way. If this card battles a monster, neither can be destroyed by that battle. If this card is Normal or Special Summoned: You can add 1 Illusion monster from your Deck to your hand, except "Nightmare Apprentice". You can only use this effect of "Nightmare Apprentice" once per turn.
