Invisible Fortress:Shadowfell pocket

Feywild pockets are small (usually) areas of Creation which have succumbed to the chaos of the Feywild.

Creation was originally formed from the Feywild, and Feywild pockets are the result of fey magic attempting to reclaim the land. Feywild pockets can be formed with powerful magic, or passively created by the presence of fey creatures over time. Most Feywild pockets were formed during the Balorian Crusade by the presence of the fey armies.

It is much more difficult to form Feywild pockets in proximity to a Reality Engine, and completely impossible if the Reality Engine is active.