FLIP: All Zombie-Type monsters gain 200 ATK and DEF. During each of your next 4 Standby Phases, each of those Zombie-Type monsters gains 200 more ATK and DEF. These effects last as long as this card is face-up on the field.
Rulings
Netrep Rulings
"Castle of Dark Illusions's” effect will increase the ATK of Zombie monsters on the field by 200 per turn for each turn that “Castle of Dark Illusions” is face-up, for the duration of 4 turns on the Standby Phase.
If “Castle of Dark Illusions” leaves the field before the fourth Standby Phase, the ATK increase will stop increasing. Any ATK increase that occurred as a result of “Castle of Dark Illusions” will remain on the respective Zombie-Type monsters as long as those Zombie-Type remain face up on the field.
Netrep Q&As
Q: Would my face-up “Spirit Reaper” be destroyed if my “Castle of Dark Illusions” was flipped face-up and do Zombie-Type monsters place on the field face-up after “Castle of Dark Illusions” is face-up receive the increase? A: “Castle of Dark Illusion's” effect is not a targetting effect. “Spirit Reaper” will not be destroyed by its effect. Any Zombies brought face-up on the field while “Castle of Dark Illusion's” effect is active will get the increase. It does not matter if the Zombies were face-up on the field when “Castle of Dark Illusions” was flipped. Curtis Schultz, 12/08/2003