Return of Tambelon (1)

During a game of hide and seek, Baby Ribbon cheats by winking out.  But the others get worried when she doesn't wink back in the second time she does this. Ribbon winks out in order to find her and winds up in a strange fog-filled city where she is chased by shadowy creatures.  Worried about their friends, the ponies rush to Megan, who tells them to spread the word to the other unicorns not to wink out.  Only Buttons gets the message in time - during a search mission, she's forced to wink out to avoid being crushed by an avalanche, and she disappears too.
That night, Megan has a dream in which Ribbon says the word Tambelon as an imposing ram closes in on them.  Paradise remembers that it's the name of a lost city that last appeared 500 years ago.  Its ruler Grogar tried to conquer Ponyland, but was somehow banished to the Realm of Mists.  Paradise correctly guesses that Tambelon is slowly reappearing in Ponyland and that the unicorns got caught inside.  In the morning, everyone is about to form more search parties when a storm hits and Tambelon reappears.  The castle gates go down and the Troggles, led by Grogar's right-hand donkey Bray, invade Dream Valley and capture most of the ponies, Grundles, and Bushwoolies.  Grogar is pleased with his conquest and vows that soon he'll rule all of Ponyland.