Team Robot's Adventure's Of My Little Pony: Friendship Is Magic Season 4 - Castle Mane-ia is a MLP/SUPS1 Crossover created by TMNTHedgehog5
Twilight Sparkle, having no luck finding information about the mysterious box, goes to the old castle of the Princesses on Celestia's suggestion, finding its old library and a diary kept by the sisters that explains the workings of the castle. Meanwhile, Applejack and Rainbow Dash, trying to find who is the most daring, go to the castle which they believe is haunted by the Pony of Shadows to try to see who stays the longest, while Rarity takes Fluttershy along to the castle to look for old tapestry to repair. These four inadvertently get into several hijinks of traps and devices triggered by themselves, as well as a unknown pony playing on the castle's organ, get separated, and run scared through the castle. Twilight finds the four in a state of panic and calms them down, and together they go down to find the organ player to be Pinkie Pie, who had followed the various groups to the castle thinking there was going to be a party. As they regroup, Twilight suggests that they all write journals that may be inspiring to ponies in the future.