Or you can use one person and drain their blood over long time.
Let’s do the math…
You can donate three times a year to the red cross (once every 112 days). According to some page, you donate around 10% of your blood volume each time.
That means, for a volume equivalent of 300 people, you’d need to donate 3000 times, which would take around 1000 years.
The vampire is going to need more people, or to keep a person alive 1000 years with vampire magic.
When you’re harvesting the blood iron of your enemies you don’t have time for ethics. A controlled study managed 4 weeks within ethical boundaries, maybe we can cut that in half unethically. So 14 days, 3000 . 14 = 115 years. So when you torture two people, you could manage to do 58 years. Better start early!
Orrrrrr capture the entire family of your foe and then you can name the sword something super cool about ending family lines
