Cool alien! I love the tendrils as primary appendages.
Whenever I do aliens, I like to picture where they came from to think about how that would make them move. Since yours has eight primary appendages (discounting the tail), and because of those awesome tendrils, it kind of reminds me of an octopus. Since they don't have bones, how would it have the structure to move about on land, as yours appears to? Well, I'm picturing something along the lines of inflatable air sacs in the same relative shape and position as bones would be. If the creatures' control of the sacs only gives them a choice of empty or full, their movement could be kind of jerky as they inflate and deflate different "bones" in their bodies. But on top of that, it could be a confusing fighting style, if they deflate their arms and swing them about with loose, curving moves, kind of like whips or ropes.
Just some thoughts in case you were thinking about doing more with this. Neat stuff!
