[jasecalde]

Of the 3 adv spells, I suppose fireball would be the best for warriors/archers since you are always assured of high damage. Plus, with their low manapool, one casting would more than likely drain all their mana and switching to their weapon of choice immediately after casting would not be a problem (since switching out wands would drain all mana regardless).

Thunder, on the other hand, would require a lot of int for magic balance, which warriors/archers would not normally have, in order to maximize thunder damage. The advantage of spamming high rank thunder would also be lost with low mana pool (and the damage is so-so).

Ice spear, may be ok. But the advantage of ice spear is its spammability because of its low charge time. Therefore, it would not be maximized with a low mana pool and casting it multiple times would be limited.

There are ways to go around the drawbacks, of course. But, in my opinion, thunder and ice spear would be better left for those specialized in magic.