ProbeDrone said: When did Dagon have tentacles? AND SINCE WHEN WAS DAGON THE FEMALE! >.< Adding the genderswap if this is Dagon, Mother Hydra would be the female one.
I doubt Mother Hydra looks anything as pleasant as this. The tentacle-legs reminds me a bit of one of the characters from the movie Dagon, though.
It looks to me more like a Formless Spawn. The blackish, fluid-looking tendrils put me in mind of that. It could be a shoggoth, though -- that would match their luminescent quality better. Pretty sure it's not Dagon, though.