So I started this breton mage and quickly discovered that enchanting was way to powerful.

for instance if you enchanted your helm / armour / ring / amulet with decreased destruction cost all your spells mana cost would be reduced to 0 combine that with the perk / skill impact and you could take even the end game boss without breaking a sweat on the hardest setting.

This is a big mistake instead of reducing it to 0 it should take 25% if what is left each time to create more balance. I say this because its make the skill tree mostly useless because if there is no mana cost why even take the perk in the first place to cast it at half cost.

As I have only started testing the warrior I cannot say if there are some big issues left, but anyone in this discussion thread can list something. But please test your theories first and then report some findings.