I'm assuming you only went vampire because of Mist Form or this is a character from the old days. Other than "personal enjoyment" or a character theme, you could have some fun with the ultimate generating morph of Vampiric Drain. 15 ultimate gained from 3 seconds of channeling, and you can cancel the channel after 1-2 seconds for less ultimate if you need to break for mechanics.
With a necro or nightblade, that is insane ulti gen in combination with their class passives + Heroism sources. On other classes it could potentially turn "just ok" ulti gen into "great" if you can work in the skill once in awhile.
Vampiric Drain and maybe Mesmerize if you need a group stun, but that's about it. And Mesmerize only works as a group stun in the initial phase of a fight or after you've taunted everything. By the time you've taunted everything the DPS probably killed them all or large majority of them. So basically it's one passive that only works when you mess up or after blocking a heavy attack, a channeled heal that forces you to drop block, and a stun with a horrible condition that has made it the single worst stun in the game. If Mesmerize just stunned everyone in the cone it'd be great.
Oh, and if Drain is channeling when you get CC'd it puts Drain on what I think is a 3 second cooldown. If you're relying on it to stay alive it might bite ya in the rear if you're not paying attention.
And I guess Perfect Scion might work.... Can't believe I'm saying that. Worst of the Blood Scion morphs and it might actually work well for tanking if you can find the ultimate to use it due to the removal of the flame, health regeneration, and cost increase weaknesses on top of the emergency full heal. Darn thing is only about 10 ultimate cheaper than the base ability though. Swarming Scion will heal you while blocking though due to the damage from the bat swarm, but it's similar to Blood Mist and without the high damage mitigation it's nothing to write home about. While entering and leaving Blood Scion you are immune to all but what appears to be siege weapon damage. Make of that what you will..