Give your Male Avatar Magic + Strength -. Pair Tharja with Ricken, Miriel with Henry. Pair your Avatar with Noire, and then pair the resulting Morgan with Laurent. Morgan will have 56 max magic as a Sage naturally. Give her Limit Breaker (+10 = 66), Tomefaire (+5 = 71), Magic +2 (+2 = 73), All Stats +2 (+2 = 75), and Aggressor. Have her wield Valflame, which gives +5 magic, for an effective 80 magic. Pair her with Laurent (also a Sage) to give several points of magic from pair-up bonuses, plus other bonuses from supports. You're probably close to 100 effective magic now, and you can Rally with other characters to go even higher. Valflame provides 16 might, and if you're attacking during your own turn, you gain +10 from aggressor, meaning you have at least 106 Attack before adding the pair-up bonuses.
It's like Pokemon all over again 0_0
For those of you who don't want to use money, then you're down 22, but still pretty well off.﻿