Tasty stuff
My only real concern is the amount of models you have on the field. Granted the C'Tan is very durable and whatever can hurt it dies. If your opponent is smart, he'll play to the mission and grab as many Tactical Objectives as possible.
Of course, suggesting some Nightscythe Warriors is going to hurt the power of the C'tan, so it's entirely your call
I like the double Tomb Blades for Maelstrom. Heck, you make me want to do an unbound list of 50 Tomb Blades for a 1000 unbound Maelstrom list, doubt the opponent could destroy that many models in a turn xD