101Volts

Though I may have dreamed more this is what I have so far:

Rarity from MLP: FIM and someone else were traveling in a mushroom patch with large mushrooms along a river, avoiding a beast that would harm or kill them on their way. Then two others showed up by them and eventually those two took a path to the right which would lead to a cycle, while Rarity was still considering the one to the left that may have led to death. Eventually I think they all went to the right, then I saw where it led: Somewhere near Applejack (Who may have been a TF2 engineer) and Lyra Heartstrings was tied up near the hole in the ground that the four came out of.