That's possible, but seems a bit suspicious if this thing is called "unseen presence". The reason I say this is that in the area that dreadful entity is spawned, the message states there is a "chilling presence", the orb that powers up before hateful entity spawns is called the Hateful Presence. There could be a connection here. It would be great if someone could get a screenshot of this. We may have found our 3rd secret boss.
Edit: found an entry for it on torhead: http://www.torhead.com/npc/aWg3VCw/unseen-presence