leandro redondo's page

If the target fails the saving throw and has a discernible head, the attack deals an extra 4d6 points of damage and the critical multiplier of the critical hit increases by 1. If the critical hit then brings the target to 0 hit points or fewer, the target is instantly decapitated and dies unless it can survive decapitation.

Does that mean that you add 4d6 to your base damage ( and thus multiply it accordingly)? Or you should add them up AFTER calculating the bonuses? In the latter case, the spell is in my opinion wildly overpriced ( It's at the very least a 5th level spell, dependant on a relatively rare condition - to score a critical hit-, with an insignificant increase of damage implied, and a secondary efect very spectacular but not so useful, in the end : They are already dead or dying, so unless you are a vampire, losing their heads it no big deal)