I missed out on a few expressions my first run. Didn't realize you could only get the cone expression in the first area for instance, but a favorite of mine wound up being fireball + expanded ae + frostfire. Hits over a fairly large area and applies burning(which base fireball doesn't) and freeze. I put that on my mage and Lantry and made that one of the opener spells I would cast. Similar setup for the ranged heal spell also works amazingly but instead of frostfire you can add the rejuvenation effect to reduce your recovery after casting it.