Tidal Wave passes through multiple enemies, which makes it a little more viable. It's sort of a baby version of Creeping Death. That said, compared to other spells that can penetrate multiple enemies, it kind of comes off on the short end. More speed perhaps would make it a little more interesting. Forest Rage I just can't figure out at all. It seems like it's designed to be a fast single target spell, kind of a machine gun, but it's limited by the global cooldown to the point that I can't find a use for it.
My go to set has been Ball Lightning and Energy Pulse so far. Energy Pulse is great for chopping through a line of enemies and/or trees. I'd almost rather see its tree-killing resource gathering function decoupled and put into another spell instead. Something that does high damage specifically to background entities but doesn't even touch monsters. Then you can drop the mana cost significantly and have something handy for when you need to go deforest a whole area.
What really leaves me at a loss is the light producing spells (and the lamps for that matter). Emit Light makes them all effectively pointless. And even with that, no area is so dark that you desperately need light spells to begin with. Some of them are pretty murky, but nothing is just pitch black.