question on runes/jewels and spell power

are there any runes, jewels, or gems that benefit spells? any rune combinations of horadric cube recipes? i've been farming mephisto and getting a lot of different weapons and runes and i want to know if anything can help my spell damage. i'm on normal offline and playing a fire sorceress.

side question: can i get any good armor off mephisto i really need something with more defense.