I’ve suggested before that the D&D vampire is too literal an adaptation of Dracula: sure, maybe Dracula’s animal form is a bat, but other vampires might turn into cats, frogs, or other creatures.
Gus at dungeon of signs suggests (among other vampire heresies) that vampire weaknesses should also be more varied than the monster manual suggests:
Likewise all [vampires] have a weakness to certain mundane things, though what exactly can harm their mortal form, or expel and extinguish their corrupted souls varies greatly: sunlight, salt, silver, cold iron, cats, living wood or blessed implements are all fairly common, though some [vampires] have contrived to have more obscure weaknesses.
I agree with this approach. I’ve made a d100 chart for vampire weaknesses.
I included the classic Bram Stoker weaknesses like garlic, plus a few dozen other common objects, creatures, and activities. The purpose of this chart is to turn vampires from a solve-once “puzzle species” into a series of “puzzle monsters,” each of which must be solved individually.
I want each vampire to be defeatable with a little investigation, so the weaknesses have to be advertised in some way. Many of the vampire weaknesses here are common items: a pale Old World noble might excite comment by recoiling from pepper or white clothes, which will be a good tell. Furthermore, every vampire is obsessed with its weakness. A vampire who fears songbirds might have an empty bird cage in its lair. One who hates lutes music might own a dozen unstrung lutes, or frequently proclaim its love of bardic music.
To populate the weakness table, I drew inspiration from the 5e trinkets table. It would be cool if some of that useless crap turned out to be a lifesaver against a vampire.
Vampire rules change: the Vampire Weakness trait is amended as follows. Sunlight hypersensitivity and stake to the heart are retained. Forbiddance and Harmed by running water are removed. Roll on the following chart to determine a new weakness. The sight/sound/smell of the weakness causes the vampire to act as if Turned. Furthermore, contact with the weakness (or being within 5 feet of the source of a sound or smell) does 20 acid damage and prevents shape change and regeneration until the end of the vampire’s next turn.
Note: this table can also be used for fairies, devils and other rules-bound creatures.
Vampire weaknesses: roll d100
13-14: Stained glass
23-24: Oak wood
33-34: The inside of a house into which the vampire was not invited
35-36: The scent of flowers
37-38: Tobacco smoke
39-40: Green flame
41-42: Cooked meat
47-48: Running water
49-50: Any water
51-52: Fey creatures
53-54: Mummies and mummified things
55-56: Old people
57-58: Dirty people
59-60: White clothes
61-62: A children’s rhyme
63-64: Music from a specific musical instrument
65-66: Being mocked for a particular feature
67-68: An ancient language
69-70: Its own name, or the name of someone from its past
71-72: The face of its victims
77-78: Bare feet
85-86: The queen of hearts, the red dragon, or another playing card
87-88: True love
89-90: Extracted teeth
91-100: Roll twice more on this table. If you roll the same result multiple times, the vampire is even more obsessed with this item, and contact damage increases by 20.