Fun one shot list for a fun day tournament.
My local game store is putting on a 3 battle single event tourney to celebrate the release of the hobbit from GW. They are doing 600 pt army lists. This is what I am thinking of going with. I know I wont win, but I think I can kill a lot of local favorite heroes and masses of troops before the day is done.

Warband 1: (army general) Witch King on Armored Fellbeast+ 3 might +3 Fate +Morgul Blade + extra Will points
Warband 2: Troll Chieftain
Warband 3: Shelob
Warband 4: Cave Drake

Was thinking about charging thier front line with the chieftain and drake side by side, calling Heroic combat or two early on to smash as many models early on as possible. Then use Shelob's and Witch King's speed to hit the rear/flanks and compel thier Heroes out for some monsterous charge/ knock down/ poison/ morgul blade lovin... If I can strike them fast enough with the new deployment rules, I might be able to crush enough "Big" points early enough to allow my army's natural terror and the witch king's "harbinger of Evil" to let me all but pick and choose favorable battles in the later rounds.

Somethings telling me your opponents wont be happy about this list since its going to give them a lot of problems.Espacially hero problems.
Your tactics sound good but I would suggest having Troll chief and Witch King together since Witch king might need a meat shield against elves,
Put Shellob and Drake together and you have a meat shield for shelob and those two together are really scary.(I speak from own experience)
Good luck!

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If you don't let me in, Frodo, I shall blow your door right down your hole and out through the hill-Gandalf