User blog comment:Dipper4561/Season 2 art!/@comment-8161155-20140731011644

Here's what I came up with:

Dipper and Mabel are being approached by a monster of some sort. Dipper is frantically searching through the journal, trying to find a page on it, and Mabel is aiming her grappling hook at it.

It's not that great, but that's the best I could think of.