OK, so after I took over as GM for my group on a more permanent basis I decided that the group should go away from my old GM's homebrew world to one of my own creation. The reason I want to leave is because I don't want to mess with his home world plus I don't know enough about his world to even try to so I would rather make a new world that I am in control and that the group can help shape through their actions and adventures. I have already given hints of what this new campaign world would be like plus they will be getting more info about it soon. So what I am getting at is that the proverbial carrot is in place in order to make them want to leave, but on the same token I get the feeling that they want to do stuff before they leave which is really going to delay things big time and just mess up the world even more. So with this in mind I am going to use the stick in addition to the carrot to encourage them to move faster.
So here was my idea to create a threat that they really could not handle and have to avoid at all costs until they are able to depart the world in of course a dramatic fashion. The story elements I have in place are going to work out well I think but I would love some suggestions for the creatures I am creating.
I call them the "Hollow Ones", they come not only from a different dimension but an entirely different Universe. They are in the natural state anti-energy parasitic beings that latch on to a host and hollow them out. Once a host has been hollowed out their skin becomes as hard as ceramic but as flexible as silk, except when the host dies in that case the skin shatters and crumbles, raise dead is not possible but resurrection might have a chance.
They are an intelligent race that live by conquering but they have conquered their universe or at least most of it. A small fleet of them have entered into ours universe and seek to open a permanent gateway to allow their legions in.
Anyways, I am looking for suggestion as to what powers they could have or would be like. I am also looking for three ranks or types of hollow ones.
Foot Soldiers: Your basic grunt type which is nothing but an empty suit of white armor, they once were humanoid but depending on their level the host doesn't always survive the process so the armor holds them together. I want them to be mainly physical types but some low level anti-energy might be good.
Officer Types: Basically officers, they should fight well but they have more powers.
Elites: These are the caster like types, they are overseers, and they should be a very real threat.
Anyways, any suggestions would be grand.