That sounds like a really cool idea! I commented in your blog, but I'll also reiterate what I said here.
The tidal forces aura needs to have an activation time. Does the damage happen at the beginning of the creature's turn, or on the maw's turn?
Also, does corpse star's grip affect every creature in the burst, only one, only enemies, or something else?
Other than those little things, I think this idea is really awesome! The one in the Monster Manual 2 is okay, but it would be cool to fight a solo version of this! Save the universe from a black hole by fighting it! Thanks for the ideas!