Pain Skull -is it worth it?

[Va'an_Majere]

Right now i'm playing as a mage, and recently after beating karador i obtained an item "pain skull". It's an artifact that increases your attack, and giving 50% rage at the same time, but decreases your mana in half. Being a mage, the bonuses that the skull grants is not really useful. But i've been holding onto the item since i knew when i deplete the spell power the skul will become dead skull, which gives 5 + intellect. But i've been in the demon land stage, and so far i've only managed to reduce the spell power to 55%. It's been pretty onerous, since i had to look for very strong to impossible fights to get 3% decrease after each fight, and numerous reloading when i didnt get it. The game is beginning to look more like a chore than enjoyable.

So my question is, is there a possible way to get better decrease for the skull? I've managed to get so far in decreasing the skull because i had leftover weak units in elven lands and freedom isles. With the +5 intellect, i can increase my intel to 51+. Right now, i already had bonuses of 46 intellect with 160 mana, and my wife xeona is holding to archmage staffs with old skull. So is it realy worth it making the game a chore by killing units with as little as possible and making the game hard for myself?