|The Blue Rainbow|
|Original airdate||March 12, 2019|
|Previous||The Cupcake Mystery|
|Next||Wranglum in Disguise|
Rose finds herself torn between responsibilities when she's asked to look after a new student on the same day she's offered to help Zack find a blue crystal.
In Twilight's class, students learn from her apprentice, Zack, about a blue rainbow that appears once every 300 years and creates a crystal upon touching Funtasia's hills. Zack asks for a volunteer to find the crystal with him, and Rose, Bella, and Lynn (evidently finding Zack attractive) are all eager to help, but Rose is the quickest to lift her hoof.
After class, Rose gets called to Principal Sparkle's office, where Sparkle asks her to look after Fabian, a new student. Rose shows Fabian around the school, but he's very clumsy, not used to his new school-issued magic mirror, and his main interest is geology (rocks). Rose's patience runs thin as Fabian repeatedly causes problems. Meanwhile, Wranglum is also interested in the blue rainbow's crystal, needing its power to help his plans of escape and destruction.
Rose sees the blue rainbow through the window, but is still looking after Fabian. He wishes to visit the academy's basement (Wranglum's lair) as its walls are made from a type of rock he's particularly fond of. Rose takes him there, but then lets slip that she wanted to go and help Zack. Fabian tells her that he's happy to stay in the basement and practice magic while she goes to help Zack, and Rose happily agrees. Shortly after Rose leaves, Fabian finds the magic portal to the forest that Wranglum has opened and falls through into the clearing with Wranglum, losing his glasses.
In the forest, Rose and Zack find the rainbow and obtain the crystal. Battiwigs finds them shortly after and is intent on getting the crystal back for his master.
The extremely short-sighted Fabian mistakes Wranglum for his mirror and calls Rose asking for help. Seeing that Fabian is near a cliff, Rose insists that to Zack that he needs rescuing. The pair fall into a pit trap that Battiwigs constructed, and Zack drops the crystal and hurts one of his wings. Battiwigs returns to Wranglum with the crystal just as as Fabian accidentally drops Wranglum off the cliff. Dropping the crystal, Battiwigs swoops after Wranglum and manages to save him, though the pair are attacked by an owl.
Down in the pit, Rose calls Fabian for help. Fabian has now found his glasses, his real mirror and the blue crystal. Rose and Zack create a pillar of light, which Fabian follows to find them, though he, too, falls down the pit. Together, the trio walk through the large caves until they reach what appears to be a dead end. Zack and Rose are stumped, but Fabian realises from examining the rocks that the wall is thin, and the three get free. They go to Sparkle's office and Fabian covers for Rose, saying that he has had an enjoyable but uneventful day. Sparkle is happy, and compliments Rose for having looked after him, and Zack for successfully getting the crystal. Sparkle adds that she couldn't imagine what would have happened if such a powerful crystal had been taken by the wrong person.
Meanwhile, Battiwigs and Wranglum have returned home to find Wranglum's lair swarming with forest critters, including the aggressive owl from earlier.
- This episode's name was formerly given as The Missing Student