Crown of command
Especially against vampire counts you have to consider the tenderizer. 5 overkill on a champion in a duel will crumble 5 skelettons, and he can also really mop up any vampires with ease. Greatskull is not really worth it and crown of command should not be nessesary if you play it right. My favorite Tyrant build is simple: Armour of Destiny+Tenderizer+luck gnoblar. No vampire build will stand up to that!
The slaughtermaster kinda needs a ward save. Mathwise it is better to have a wardsave than the cookbook, and it also helps in combat. I like Fencers Blades+talisman of preservation. It makes him near unkillable and very strong in combat generelly. I know other people like the bloodcleaver for its healing.
The problem is, at 2000 points it is hard to squeeze in both an effective tyrant and slaughtermaster. I would consider downgrading the slaughtermaster to a butcher or simply leave him out.
BSB (Banner of Eternal Flame)
I understand why you want the flaming banner, but I would suggest putting it on a unit of Ironguts. Instead you should buff your BSB up to desent defensive and offensive ability. CLS, heavy armour, enchanted shield and wyrdstone/other ward save plus a luck gnoblar will do the job.
The Butcher should have a dispel scroll if the SM doesnt. You are going to need it!
...more later... running out of time...