what is this O.o

[sinulf995]

[plowmanplow]

That looks like a rift from the Dimensional Doors mod

[Lethosos]

The bigger ones tend to spawn Endermen.

[Epikos1994]

It´s a rift from the dimensional doors mod, all i know is that they slowy spawn endermen and eat blocks.

P.s. Couldnt you have posted this same picture onto the post with the portal ?

http://forums.technicpack.net/threads/what-is-this-o-o-left-screen.41365/

[Malawi]

To make it go away, use a rift remover. To make it stable, put a dimensional door right under the rift.