how do you slay a castle full of vampires?

[Doctor Awkward]

The plane of positive energy explodes you if you reach too high hit points and fail a fortitude save.
Since the death on excess of positive energy is an effect that does not works on objects and is resisted by a fortitude save then undead are immunized to it.

Who says it doesn't work on objects?

That would explain why the plane is a barren wasteland with nothing but energy.

[jintoya]

How big a kingdom are we talking about? If it's any decently sized storm drain system we are dealing with, I'd be careful then with the flooding plan. Especially if your DM is really deep into world-building and infrastructure.

An inch of rainfall over a square mile is a million gallons of water. Cities that size have drainage systems designed to handle well in excess of that kind of runoff. The flashflood spell creates just under 750,000 gallons in a single casting, so it would be nearly impossible to completely flush a city-sized storm drain with that method.

It's fairly big, not sure about population, it's small enough that the flash flood spell will flood it... But I've secured a gate to the holy ocean at the base of the mounting plains of heaven by calling in a favor, so... Infinite holy water.
I'm opening it on the top floor of the castle, just did an entire session of prep work

I've got an army of loyal demons to seige the town.
it just snowed, so making it sunny will be reflective and I'm seeing up a few payed casters to scry for escape vampires so I can hunt them all down, there are at least two I suspect will escape, both are sorceresses and are suspicious of us, so I'm sure they have a backup plan

[Yael]

Step 1/2 - protect your Tsundere. Of course, she may make applying touch spells difficult.

I-it's not like I need your protective spells! D-dummy!

[Calthropstu]

Slaying a house should be a simple matter with a sledge hammer.

If the vampires will interfere, simply wait until day time when they can't come outside and go to work.

All joking aside, this very well may be the way to go. Destroy the castle and forcibly expose them to the sun. If you can bind an elemental with disintegrate, do so many times and blast the castle with thousands of simultaneous disintegrates, destroying their protection from the sun and poof.

[jintoya]

Slaying a house should be a simple matter with a sledge hammer.

If the vampires will interfere, simply wait until day time when they can't come outside and go to work.

All joking aside, this very well may be the way to go. Destroy the castle and forcibly expose them to the sun. If you can bind an elemental with disintegrate, do so many times and blast the castle with thousands of simultaneous disintegrates, destroying their protection from the sun and poof.

this would be cinematic as hell, and likely a better solution than the hundreds of demons i summon.
i imagined that scene from harry potter: deathly hallows pt.2 where all the evil wizards blast the castle with a magic volley.
i usually use legion demons to do grunt work, and the only motivation they need is to fight and wreck things...
i was building a loyal demon army long before this happened...because i am going to lay seige to the 6th layer of the nine hells (i think knocking Glasya from the throne and creating a power vacuum is a great way to end a campaign.)

[jintoya]

I-it's not like I need your protective spells! D-dummy!

not entirely incorrect, she gets possessive of "her servant" when people assume i'm up to no good, because she knows he wouldn't harm a fly. (unless it were a fiendish fly.....dire fiendish fly, that is an interesting monster idea)
Dimitri and her have a good dynamic as far as roleplay goes, but her standoffish attitude helped us when taking to some of the vampires, i kinda think they have their own plans...and yesterday i found a traitor in their midst.
the plot thickens.

[Telonius]

Multi-part plan.

Part 1: Frame Job. Surreptitiously start teleporting the hostages away to someplace safe-ish. Be sure to knock them out and draw a little bit of blood to smear around just before you do it. When it's been noticed that the foodstock has started disappearing, start sowing discord among the vampires. Clearly somebody's been sneaking midnight snacks. See who's suspected, and leverage that. (With any luck, at least a few of the vampires will attack/kill each other just on principle, decreasing the number of them that you'll have to fight).

Part 2: Grand Vizier. Offer your services to the Head Vampire to root out who's been offing the meatshields. Figure out who the second-most-powerful vampire is (other than the head guy), and manufacture some evidence that they're behind it. Pin it on him and his supporters. Make sure Head Vampire wins the power struggle and executes the other guy.

Part 3: Witch Hunt. Offer your services permanently to the Head Vampire. Start finding more and more "evidence" of treachery. Keep teleporting the hostages, this time without leaving blood evidence. This time, forge some messages to show that they've been ordered away on some mission that's against the orders of the Head Vampire.

Part 4: Praetorian Guard. When the ranks of the castle have been sufficiently depleted, offer to "recruit" some of your demons (and whatever other people you can trust to fight, friendly-ish Clerics if you can find them) to serve as "additional security."

Part 5: Endgame. With the vampires whittled down and your own people (and I use the term loosely) in charge of strategic choke points, begin your final assault. Whether that's standard physical combat, daylight exposition, or flooding the castle with a river, doesn't matter too terribly much. You'll have surprise, tactical advantage, and (possibly) higher numbers of combatants.

[noob]

Multi-part plan.

Part 1: Frame Job. Surreptitiously start teleporting the hostages away to someplace safe-ish. Be sure to knock them out and draw a little bit of blood to smear around just before you do it. When it's been noticed that the foodstock has started disappearing, start sowing discord among the vampires. Clearly somebody's been sneaking midnight snacks. See who's suspected, and leverage that. (With any luck, at least a few of the vampires will attack/kill each other just on principle, decreasing the number of them that you'll have to fight).

Part 2: Grand Vizier. Offer your services to the Head Vampire to root out who's been offing the meatshields. Figure out who the second-most-powerful vampire is (other than the head guy), and manufacture some evidence that they're behind it. Pin it on him and his supporters. Make sure Head Vampire wins the power struggle and executes the other guy.

Part 3: Witch Hunt. Offer your services permanently to the Head Vampire. Start finding more and more "evidence" of treachery. Keep teleporting the hostages, this time without leaving blood evidence. This time, forge some messages to show that they've been ordered away on some mission that's against the orders of the Head Vampire.

Part 4: Praetorian Guard. When the ranks of the castle have been sufficiently depleted, offer to "recruit" some of your demons (and whatever other people you can trust to fight, friendly-ish Clerics if you can find them) to serve as "additional security."

Part 5: Endgame. With the vampires whittled down and your own people (and I use the term loosely) in charge of strategic choke points, begin your final assault. Whether that's standard physical combat, daylight exposition, or flooding the castle with a river, doesn't matter too terribly much. You'll have surprise, tactical advantage, and (possibly) higher numbers of combatants.

The only problem is that vampires are already plotting so much that actual plotting is less efficient than just subtly making vampires believe there is a plot against the vampire lord and see everything crumble as they get more and more confused because there is no traces at all of the plot(because it is just a rumor and not an actual plot) and then they all killed each other before you summoned twelve demons for the destroying part.

[daremetoidareyo]

Secretly cast hallow on certain structures? Offer your help to find the insurgent responsible. Inquire as to areas that absolutely need protection from the hallowing. Congrats, you found what areas to get sunlight into.

[jintoya]

Secretly cast hallow on certain structures? Offer your help to find the insurgent responsible. Inquire as to areas that absolutely need protection from the hallowing. Congrats, you found what areas to get sunlight into.

not a bad idea
http://www.d20srd.org/srd/spells/hallow.htm
attaching spell effects to the hallow could also hinder them in other ways, especially if i can make it hard to undo somehow, it could be made to look like a real epidemic that i can solve, alleviating some suspicion from us and gaining some trust in the process.

[atemu1234]

Blow the roof off the place?

[Son of A Lich!]

I'd recommend, if you have the charisma to pull it off, turning the vampires against one another and sowing doubt among the thralls.

Vampires are created in subservience to their master, the vampire that sired them. While they can't actively oppose their master's will they have precious little freedom where ever the "ink touches the paper," so to speak. Fostering paranoia between the Lord and his Sire who could stage a coup on his house will lead to them clearing out plenty of the internal forces for you.

Thralls are not in the same boat, they are literally dominated. However, that doesn't mean that their loyalty can't be split between an internal cold war of domination amiss the higher level vampires in the house.

at Dusk, after the vampires have left and resumed their normal responsibilities, go into a bedroom and clean a coffin of it's grave soil; do this to which ever Vampire sire is most loyal to the Lord of the manor. Watch the antics ensue.

Offer use of Zone of Truth on the members of the household and ask them leading questions that test their loyalties.

If your cover is not blown, only take risks that incriminate someone else. If your cover is blown, hold out until sunrise and run.

[jintoya]

it went somewhat fine, a few escapees, but i will track them down, it was the sorceresses...i am having trouble locating where they went off to, so i expect there to be a part 2 to this...

summoned the demon army
proposed the toast with holy water that was transfigured into wine through a temporary effect, when it turned to holy water, they fried.
i then opened a portal straight to the silver sea (did a favor for the shields of Bahamut, so he did me this favor)
the castle flooded with holy water, killing nearly all the vampires, i then signaled the demon army to storm the city, they were instructed to throw all the coffins they can find out into the sun (control weather)

what i didn't count on was the riot that took place as the vampires lost control, some fled the demons, many instead went "the enemy of my enemy!" and also tossed the coffins into the sun.

the churches were full of impostor clerics, the basements to the churches were where the human cattle were kept.
so after a bit of a challenging fight, i freed the prisoners.
found a few vampires that were hiding in smoke form in dark places, a few escaped, and i am unable to track them (i find it unlikely that they escaped via gate or portals, analyze portal turned up nothing in the castle.)

[flappeercraft]

it went somewhat fine, a few escapees, but i will track them down, it was the sorceresses...i am having trouble locating where they went off to, so i expect there to be a part 2 to this...

summoned the demon army
proposed the toast with holy water that was transfigured into wine through a temporary effect, when it turned to holy water, they fried.
i then opened a portal straight to the silver sea (did a favor for the shields of Bahamut, so he did me this favor)
the castle flooded with holy water, killing nearly all the vampires, i then signaled the demon army to storm the city, they were instructed to throw all the coffins they can find out into the sun (control weather)

what i didn't count on was the riot that took place as the vampires lost control, some fled the demons, many instead went "the enemy of my enemy!" and also tossed the coffins into the sun.

the churches were full of impostor clerics, the basements to the churches were where the human cattle were kept.
so after a bit of a challenging fight, i freed the prisoners.
found a few vampires that were hiding in smoke form in dark places, a few escaped, and i am unable to track them (i find it unlikely that they escaped via gate or portals, analyze portal turned up nothing in the castle.)

Well it seems like it was well carried out even if some escaped. I'm glad you used the holy water on the drink idea, I've been wanting to use it or see it used for a long time.

[jintoya]

Well it seems like it was well carried out even if some escaped. I'm glad you used the holy water on the drink idea, I've been wanting to use it or see it used for a long time.

it worked really well to ensure that all the most powerful of the vampires were destroyed right in-front of me...so i know for sure.

also, it worked well with my tsundere drow, because she just sat back and made a dismissive gesture toward me and with a "go get them already." my vampire killing spree began...it fealt really good to have a plan come together for once.

now i will begin my siege of the 6th layer of hell...building a loyal demon army is hard because they are backstabbers by nature. so far i have been doing well to avoid demons who don't just like destroying stuff, this makes them easy to motivate.

[Ellrin]

I would start by planting a yearning for tea in their collective subconscious...

[jintoya]

I would start by planting a yearning for tea in their collective subconscious...

Then, kill or buy all the tea businesses in the area... But don't sell to them until they are rabid for it and will pay an outlandish price... Put them in debt and make them sell the castle to feed the need... Evict them on a sunny day... That's where you were going with this... Right?