


I know +weapon skill enchants stack, but I haven't really played with them. Voldun mask reduces prices, then equipping the Amulet of Zenithar reduces prices again, though I haven't checked to confirm it's additive (i.e., it should be 20% + 15% is a 35% reduction, which is close, but I haven't confirmed it). Fortify alteration/destruction are additive, so four 25% mana reduction enchants stack to 100%, or zero mana cost. I have boots and gloves of +37 (I think) carry weight, and they stack additively to 374 total (from 300 base), and stack with my Voldun mask which adds another 20.

I can confirm that +carry weight, fortify alteration/destruction, better prices, +health, and +mana all stack.
