If another Zombie monster is Special Summoned from your GY while you control this monster (except during the Damage Step): You can draw 1 card, then discard 1 card. If this card in the GY is banished face-up to activate an effect, or by an effect: You can Special Summon this card, but banish it when it leaves the field. You can only use each effect of "Shinobi Necro" once per turn.
