Is there any way to increase the damage of vampiric drain past 5/s besides drinking a fortify destruction 3,000,000% potion? I don't care if it's a glitch, I just want moar powa.

Oh well

Having Seranna with you (for some odd reason) weakens you profoundly. So, if you do have her as a follower, switch followers and try it again. You should notice a big difference.

Nah, I just mean the standard 5hp/s of a stage 4 vampiric drain is way too low. I was hoping there was a way to boost it beyond that other than drinking a potion at the start of every battle.

It does svck that you can't amp it up more, but hey, at least you can have fun flinging people about the villages!