By the way, for a few levels I too felt that Shale was pretty mandatory because the rest of my party was dropping very quickly. Everyone else could croak and I could keep him alive with one healing spell from my hidden mage and a few healing pots while he beat up 2 or 3 monsters. It was only after I got some decent CC and AOE (which I hadn't concentrated on when selecting skills early in the game) that I found Shale to be entirely unnecessary.
Again, I think the lack of a decent manual can make the first play-through of DA very, very rocky (Shale pun!) because it makes it possible to select classes and skill sets that don't have any synergy. By the way, has anyone posted any of the best combos like those you listed in your post? There are supposedly 10 unique spell combinations, but I only uncovered one in my first run-through. I hate to start another DA thread at this point, but I'd love a breakdown of some tactics that everyone uses without having to wade through 6 or 8 threads.