easy way to do this would be to mod the damage to them. What i would is is load esm >open object window>filter for"vamp" you will see a bunch of npc files look for the ones EncVampire0#Template 1-6 ...this is kind of a master template for different kinds that spawn at different level brackets. adding a perk to these will add it to all of the vampires that get their data from it IE the nord, imp ,elf ,boss 0#s click on spell list tab> go to perks window > pick new > give it anyname/ID and go to perk entries window and pick new >pick the entry point tab>look for Mod Incoming damage> for function pick multiply value > put in a value (0.5 would give then 2x effective health) once you did it for one level set you don't have to make a new perk simply add the perk you already created. (you can make new perks if you wanted) Its good because if you test it out and find you want to change it a bit, just search you perk and change the value. TONS of other tweaks you can do with entry point as well if you play around with it. hope that helps