Dark Boo

Dark Boos are purple Boos that appear in Paper Mario: The Thousand-Year Door, Super Paper Mario and Mario & Luigi: Partners in Time. They may be found only in the hidden spot of the Poshley Sanctum, Underwhere Road, and also in the Pit of 100 Trials. Dark Boos are more powerful than their white forms. In Super Paper Mario, they hide in 3-D, waiting for somebody to walk by. Then, they flip to 2-D and attack.

Dark Boos reappear in Mario & Luigi: Partners in Time in the Gritzy Caves area, once again stronger than a normal Boo. A Dark Boo's only attack has it appear behind a brother and ram him. If it opens up its right eye, the attack is aimed at Mario. If it opens up its left eye, the attack is aimed at Luigi. If one of the Mario Bros. is attacked, the Dark Boo steals either a normal Item or a Bros. Item and will flee with the item on the next turn if not defeated quickly. They are usually encountered in large groups, rarely appearing alongside other enemies.