Darth Extecute
Time is of the essence
Kil'Jaeden is the master of the mind.. Most likely one of the best mindworkers in the warcraft universe ((That's an impressive feat, fyi)) and since he's a master of illusions, he could mess Nihilus mind up.. Fool him of things that are there and that arent.. Make him see things.. Feel things.. And as seen in warcraft, I didn't exhaterate a lot.. Illidan, Vashj and Kael'Thas is but a finger of size compared to Kil'Jaeden when they encountered, and that's not even a third of how big he could turn.. If he turned any larger, he'd have gone out of outlands and that wouldn't be agile ((that's what has been seen.. I dont think there's a limit to his shifting.. ))
And since Kil'Jaeden was the one giving the Lich King his powers, Kil'Jaeden logicly should be capable of doing the things he taught the lich king.. And the lich king could control thousands ((seperatly)) with only a thought..
The force kill could possibly function, if Kil'Jaeden let him.. As I said.. Illusions.. Sizeshifting..
He also is said to being capable of defeating Archimonde.. Archimonde is highly effective one when it comes to fighting individuals.. He could probably crush Nihilus.. Velen acknowledged that Kil'jaeden was his, as well as Archimonde's, superior in matters of the arcane ((Velen and Archimonde is truly powerful entities.. You do know this, and I know you do)).. The arcane in warcraft sense, meaning space, energy, souls, starpower and pure magic.. If Nihilus was inside his ship, Kil'Jaeden could crumble that ship, probably without touching it..