Is there any strategy to this? Because I'm not seeing any -- game seems to be entirely luck.
You could have a "safe" 3+ that ends up being the vampire. Meanwhile, you could have a 50% chance with a 9+ that you may as well take by staking it, but still 50% chance you'll lose that.
Only thing I try to do is take "risky" guesses early on, where the penalty is less, but still.
You can sometimes confirm with 100% what the vampire is, but most times you cannot.