I think decreasing the Vampire Lord's HP might make this more reasonable. Right now it's out of Oty range even unupped, Shockwave doesn't kill it, isn't threatened by Paradox, and takes a fair amount of quanta for a lance or siphon life to deal with it.
Even if it is fine like this, what happens when it gets buffed? If it becomes an 8/8 by blessing, does it still only do +/-5 to your HP and your opponent's HP? Is that reasonable to code? I'm not sure. Does it only increase the cap of your max HP? I assume it also has the vampire ability built in, but just something that could be unclear.