Even a baby can conceptualize a better episode… and your cliches are nothing compared to Hasbro's and IDW's.
The Mane6 receive rainbow bracelets which lets them know where there's a magical problem. The ponies enter a green valley with golden bridges and small pink castles and estates. It's far prettier version of Ponyville with Canterlot and G3 elements.
The ponies in this town either have their cutie marks hidden or have multiple cutie marks on them, some of the cutie marks are bigger and more exquisite looking like G3's. The ponies are highly talented, exceeding at natural magic beyond their imagination.
They talk to Starlight in charge who says they've lived there for thousands of years in Dream Valley, but all their powers fade away the moment they exit the area.
The Mane6 think of reporting back to Celestia their findings, but can't recollect anything specific the moment they exit the town. Merely the location of it, which later also gets foggy and only their magic bracelets guide them.
The mane6 enjoy their time in dream valley and slowly but surely get charmed by the townspeople and , who have a soothing spirit-like charm.
They appear to get charmed and they live there for a couple of days till slowly they drift out of the spell, but subtly poke around and find a cave full of magical weapons, artefacts and a room full of floating orbs which viewed through a crystal lens shows every cutie mark.
Twilight disguises herself as a mirror and mind welds Starlight into revealing the truth that she was gathering power to take over the land. Starlight breaks the mirror and fights with all of the Mane6 at once. She reveals her true form as a large spectral horse of sorts. She is defeated, but not before trying to bury the entire valley on top of them. The townsponies disappear and so do the artefacts and magic.
The mane6 come out alive as the valley vanishes under their eyes.
Any ending could work. Any conclusion. Anything is superior to Hasbro's.