A good example is Wizard 1st Chill Touch, Will save or flee in a panic.
That's pretty risky though. A caster standing in melee targeting it's touch AC and hoping not to get hit and level drained and hoping the vampire fails its will save is not likely to end well for the caster.
You could try to take advantage of their mirror/holy symbol aversion; have one or two people use them to keep it at bay while ranged or casters attack. The description also mentions that they won't enter areas with a strong garlic scent, but it is unclear if they are actually impeded or just don't like to.
Protection from Evil or Magic Circle are also good ideas to help with the dominate. See Invisibility would also be a good spell to have prepared as you definitely don't want a Greater Invisibility vampire on your party.
Fight dirty! Use any possible advantage you can gain and hunt proactively if possible. Nets and the drag combat maneuver could come in really handy if you hunt during the day... Detect Undead and Locate Creature can be great tools to this end or even to spare you the trouble of being ambushed by vampires. Protection from Evil is another solid standby for casters and Searing Light might be a good option too. Don't forget your holy symbols too! Oh there is also Display Aversion in Blood of the Night.
My players have had a really horrible time dealing with one vampire whose very fond of using potions of Haste and Displacement to combat them, I don't see why you couldn't turn the tables and do the same to your vampires. Happy hunting.
I ran into a similar situation with a group once. Fortunately we were aware of the vampire's location, so we were allowed to get the jump on them.
Obviously we attacked during the daytime, and spent a few hours aligning small steel mirrors to reflect a beam of sunlight all the way to the door leading into their chamber. Opened the door, and the rest of the fight was mostly us grappling and bull rushing the vampire into the beam of sunlight.
Worked for my group, but it's definitely not an encounter to take lightly. We did, as was previously mentioned, have tools to deal with invisibility and had protection from evil. We were also very lucky that there wasn't an exit from the room available via gaseous form, and there were no other minions there for us to have to deal with. No idea what sort of situation you'll encounter, but good luck!
Take a page from Van Richten's Guide to Vampires: do your homework, scout the location if possible, prepare yourselves and the battlefield, try to fight them on your terms, be ready for the plan to go wrong.
1. Have scrolls of consecrate and glitter dust at the ready. It can't create new undead and it gets penalties to everything. It will also go invis and see invis is self only, sadly. Faerie Fire might also do the trick.
2. Defensive spells like Blur and Displacement works just fine against vampires. They usually have blind-fight, but that doesn't mean the spells are useless.
3. Bring anti-swarm tools. Alchemist fire, scrolls of burning hands and color spray are cheap examples.
4. Illusion spells in general might be handy. Figments and glamers work fine against vampires and the swarms they might call upon. A major image of tons of garlic that's all over the place WILL screw a vampire if he fails his save. Sadly, a vampire has great saves :p
5. Make sure every single party member can damage the vampire.
6. Magic Circle vs Evil and try to stay together!
7. Eat garlic daily.
Given that you can run into vampires at this level (or even sooner) what would you recommend? Most strategies I have seen are either high level (sunbeam) and costly (disruption weapons).
About all I can figure is Halt Undead (hope you're lucky) and carry lots of stakes...what else at this level? Well that and Protection from Evil to block domination. Any negative energy protections at this level?
I suppose try to keep them busy with summoned mobs maybe...but they are intelligent and can fly, gaseous form, etc...
Don't forget, Vampires aren't CR=9. They're a template that can create all sorts of different CR levels, the CR=9 is just an example of a vampire. If you're GM, build up some lower level minions using the template. Have 'em run into a group of CR=4 or CR=5 vampire aristocrats. Bust out a CR=6 Summoner Vampire. Create a small evil ceremony with some low level vampire warriors and a CR=6 Vampire Cleric. Etc.
If you're not the GM, and you're asking because the GM mentioned he's throwing vampires at you? Point this out to him, that he's not just stuck with the CR=9 monster in the book.
Garlic, stakes, and if you can create some sort of magic to make a house vampire have to be invited inside to enter.
Really though, if the PCs know vampires are around and a problem the best way to handle them is careful preparation. Vampires can't come out during the day, so thats when the PCs operate, during daylight. At night they're in their impenatrable home safe from univited vampires. During the day they scout around to try and find the vampire lair, but avoid going inside anyplace where daylight can't be easily reached (unless more prepared). Once you've discovered their location you prepare some traps for them and lay in wait for them to come out at night. With some good preparation and luck you might be able to hold them off. If you're not prepared and can't get to sunlight, you're pretty much SOL.
