Rosemary Tea
Auror
Vervain is EXTREMLEY bitter. So bitter that more than a small dose of it can cause vomiting, just from the bitterness. (I speak from experience: I once made a vervain infusion to help with anxiety I was having--vervain is a good treatment for anxiety--and half a cup of it made me puke).
No way would it be in there just for flavor. If anything, you would need to mix a sweeter herb with it to make it drinkable. For that purpose, lemon balm would be great. It could also be a magic ingredient in this anti-strigoi potion. One of lemon balm's uses in herbalism is to treat the emotional trauma of sexual violence. Not for nothing does all the lore about vampires make their attacks highly sexual. These strigoi victims have been the victims of the ultimate sexual violence, arguably, so what's going to save them from turning is something that heals that trauma.
Another plant that might be in there is yarrow, which is also pretty bitter--you'll need lots of lemon balm to balance that and vervain!--but yarrow has a long history of use for psychic protection, in whatever sense "psychic protection" has been viewed culturally, and it's associated with long life.
