In principle, you should develop your character like this: /post/13979/.
I agree that you need to focus on Light Magic because:
1) It greatly enhances the Elven army.
2) One of the Elven heroes has it as a starting skill (Ulfina, specialist in unicorns), which doesn't hinder achieving the fatal ability.
3) IMHO, Summoning magic is weak.
4) We shouldn't forget about the "Holy Word" spell.
To protect against magic, use Unicorns (if the enemy is a Dark Elf, nothing will help – the “Destruction of Spell Protection” ability affects all your units).
The most important skill, I think, is "Stalwart Defense." When Ents are rooted, it increases their defense by 50%; with this ability, it’s 110%.
м/ф "Ёжик в тумане" качать здесь: http://www.basabas.com/blog/page.php?itemid=1584 .