It all depends on the vampires in your mythos.
Some are well-nigh ludicrous - indestructible machines against everything except some odd-ball Achilles' Heel(s) - while others are more "plausible".
The Revenants/Vampires I came up with for one of my Wi P
were vulnerable to a lot of things that would kill any
Starvation (you've got to fuel your body, regardless of how invulnerable it is and if you're expending vast amounts of energy healing from wounds or performing superhuman feats, then your dietary needs probably exceed those of less capable lifeforms.)
Beheading or sufficient damage to the brain (remove that and functionality departs pretty quickly.)
Drowning/suffocation or any other means of incapacitating the lungs (the laws of physics/chemistry dictate that if you can't oxygenate your food to provide the requisite energy, you die.) This includes having your lungs destroyed by a suitably-sized weapon.
Fire. 'Nuff said.
Thirst (everything needs water to function properly).
Destruction of heart (if it can't pump blood/nutrients around the body, the body stops working).
The key being complete
destruction/removal of brain, heart or lungs - a serious wound that would incapacitate or kill a human may be survivable if there's enough function left to survive long enough to heal (and they heal fucking quickly
To which is added: "allergy" to certain plants (garlic, rose, ash, white oak and hawthorn) the juice/sap of which can cause serious aggravation of any wounds, increasing damage received as well as impairing the healing process considerably.
A stake through the heart would seriously impair them (it'd kill
most things) and would prevent healing until such time as it was removed (which is usually easy for a large stake - grab and pull). A stake of rose, ash, white oak or hawthorn (or has been soaked in garlic oil) would cause a wound that takes longer to heal after having been removed.
Other than that, Holy Water would only make them wet and religious symbols are only effective if you make them from garlic, rosewood, ash, white oak or hawthorn...
... then somehow force the vampire to eat
In the case of my vampires/revenants, a gun that fires bullets that have garlic oil in them would do serious damage. A shot to the heart or brain would be quite devastating and potentially lethal to them, especially if it fragments nicely and scatters highly motile oil throughout their vitals causing aggravated damage.
Traces of garlic oil getting into the bloodstream and being carried throughout the body wouldn't be pleasant, either.
Then again, a 12ga full of steel bird shot to the heart from about 4-5 yards (at 1" spread per yard, roughly) would probably stand the same chance of killing them - that crater where their heart used to be would be "problematic"...
But if your vampires heal from the most ridiculous wounds because of some dark magic, then you may need something with more "oomph".
edited 18th Feb '14 12:48:25 PM by Wolf1066