Zenith Chaser is a climber. It says so in her cutie mark. But the world of Equestria isn’t that big, so there are no more mountains to climb, and now she simply dragged Pinkie Pie along to climb an iceberg.

A millennium tending to a moon that was not her creation has taken its toll on Celestia's body and magic.
Before she goes, Emerald (Spike's new form) must learn her art and create a new sun, with Luna's help.

Uses season 2 canon.