I am making a homebrewed campaign where my players are vampire hunters in a world infested with them. They will be starting at level 3. Currently there are very few vampires made for DND 5e and I am struggling to find a substitute that would be fair for them to fight. I have been a DM in the past but never had to homebrew like this before.
I have an idea of doing a 5-tier system. Tier 1 being the lowest with vampires who are completely in control of the vampire lord, unable to think for themselves and mainly taking the offensive rout. Tier 2 is able to think more clearly, but only enough to plan their next attack. Tier 3 would be like how they were in their human life, just more advance. I was thinking of allowing them some simple magic at this tier. Tier 4 is more advanced, able to use magic probably a CR 7. Tier 5 would be my bbeg, he can only be defeated with an object older than him.
Any ideas on how to make this happen?