This guy is IMMORTAL, he has had centuries to plot and scheme. Forget "Plan B", this guys Plan X, Plan Y, Plan Z, Plan AA, Plan BB... He has had an endless amount of time to prepare for any encounter. Long before the PCs knew he existed, his network of minions warned him about them and he figured out all of their weaknesses and strengths. With hundreds of years to prepare, even 2-3 levels as a spellcaster can do amazing things.
Imagine just turning invisible for an hour a day, walking around using Detect Thoughts to spy on local merchants and nobles. Your knowledge of their dirty little secrets would be far more frightening to them than any Fireball. Cast Charm or Suggestion on a random person every day for 300 years with a simple command like "Love me and tell everyone how great I am." You would end up being worshiped and treated like a saint.
Stop worrying about silly combat tricks and really think BIG, look at the broad scope of what this character can do long before the PCs ever encounter him...
actually you make a very strong point along with what the others have said and with all the extra bits of vampire lord such as sensing through 10 miles of summoned creatures, I was thinking too much like a combat situation, I'm thinking of a few levels in the black guard with some wizard levels (party is 4 people all level 8)..but I shouldn't have restricted myself to thinking about the encounter alone heh. these players are gonna be in for a real treat, thanks everyone!