Crystal of Nightmares

The Crystal of Nightmares is an evil magic crystal ball that possesses the powers to influence the dreams of individuals and drains them of their own self-confidence. It first appeared in the titular episode "Crystal of Nightmares" of Mighty Morphin' Power Rangers.

History
At school, Kimberly and Trini are worried about an imminent science test; the boys, however, are not, since they are planning to go to Billy's uncle's cabin to study all together. Of course, they invite the girls.

Bulk and Skull, meanwhile, are having trouble of their own: Mr. Caplan gives them extremely bad report cards, and tells them that if they take another "D" in the next exam, they will be put in detention for a very long time. Bulk decides to follow the "geeks" to spy on them while they are studying, in an attempt to cheat and get them in detention.

On the moon, Goldar is revealing his plan to Rita Repulsa: he reactivated the Crystal of Nightmares in order to cause the Power Rangers to lose the confidence in themselves, making them easy targets.

At the cabin, the gang go out to eat after an afternoon of studying. Bulk and Skull (dressed up as maids) enter searching their notes, but the boys quickly come back, forcing them to hide under a bed.

During the night, Rita's general put his plan in motion: the Rangers dream of the worst moments of past battles, and share a nightmare in which Zordon strips them of their powers. This leaves them afraid and shaken so much that they are reluctant to go to stop Goldar once Zordon tells them of his plot. At the cave where he is hidden, the teens are easily pushed back by the Putties since they don't believe they can win. Though scared, Jason is the only one that reacts enough to go past the Putties and Goldar and manage to destroy the Crystal, giving back to the team the confidence. They then defeat Goldar and Scorpina and hurry to school. Bulk and Skull, who slept during the entire ordeal, do the same.

The Rangers all get "A's" on the test, while Bulk and Skull both take "F", meaning a long period of detention for them.