The dread seeded idea is looking more likely. Apparently there is a title that can be unlocked related to dread seeds.
On a related note I got the chance to kill some of the Dread-Seeded beings on the PTS
Tatooine: Sand Demon
And found that they seemed tuned for 2+ players. The one on Tatooine has a regenerate ability that gives it a 10% that it will use twice within 9 seconds, thus forcing you to bring a 2nd player (if only for interrupts). I suppose a person could run a way and then charge it to interrupt the heal, but it's clearly meant for 2+ people. I two manned it (no companions) in full Arkanian and it was easy. I suspect it's meant to be done with either 6 people in Dread Guard or 4 people in Basic (level 66 gear).
The Wampa hit a bit harder than the Sand Demon but not by much. The Wampa had either an interrupt or a really short stun.
I haven't bothered with Lucky on Corellia, but apparently someone on the PTS has already tried using the Orb on Lucky so it's not the Dread-Seeded Rancor. I'm curious if the Dread-Seeds have anything to do with the Terror from Beyond or some ancient weapon on Lethon (aka Rakata Prime).