When I had trouble killing orcs early on, I took 1 level of Freeze (later 2). Would not have been able to kill War drummers without it. Later it was useful against Lizardmen, but I had other skills so it wasn't needed.
Anything else I wanted to Freeze tended to be immune <img src="/ubbthreads/images/graemlins/disagree.gif" alt="" />, so I decided my Survivor needed some magical damage. Tried Spinning blades but rather than it doing 20 damage as listed it tends to do 6-12 too often and I concluded that recasting Restoration as needed while in melee combat is more mana effective.
I ran into a couple boss-type monsters and was not able to reliably hit them with bow or dagger, so I took Lightning skill. Liches tend to resist Lightning too much, but most other level 20-30ish monsters are good Lightning targets. It's important to note that you can re-cast Lightning as fast as you can click the mouse button, which essentially makes it better than any weapon I've seen.
Only need Lightning level 1 and click-click-click-click, etc = monster dies in 3 seconds. Especially useful if the monster heals itself, like Lizard Fanatic, because they don't have time to heal.
At character level 16-21, my favorite skill has been Wall of Skeleton(bones).
Its NOT a "wall" but an instant summon of 5 skeletons at once. Never train Summon Skeleton, when you can wait and get this skill. It is great to summon these blockers if you like to use a bow or spells to do most of your damage, or even if you just want to keep a bunch of monsters busy while you hack apart the ones closest to you.
I have not tried any poison or trap skill yet as I have not needed it.
There was a book of Restoration that I could not pick up for some reason, it being near the edge of the screen. I trained Telekinesis and was able to pick it up, at least I assume it was the Telekinsis click I did...
