I made a little modification in the exp_system.lua
Code:
local maxhp = Attack.act_get_par(attacker,"health")
Attack.act_attach_modificator(attacker,"health","expa_health_"..tostring(chp_health),maxhp*chp_health*expa_hp_par*0.01,0,0,duration,false)
it works well enough on small numbers but on larger bonuses for your units it gives a grater bonus than supposed to. While in tactics mode or before summoning Asmodeo/moving units the current hp is calculated correctly but after the first move it goes a few points up. This must be some kind of unit conversion or whatnot issue. Anybody more experienced feel welcome to explain.
Also I can post screens showing the matter clearly if needed