The minimum damage is half of the maximum damage. The damage caused by this spell is 2.5 times more than berserk spell. Exact damage formula is not known yet but at skill level 100 and with a 50 attack weapon, this spell causes approximately 480 damage on average. If you use an enchanted weapon and cast this, it will lose charges as well (and make some damage with the element). Also note that this is the highest level spell in Tibia.