I actually like the Tidal wave spell, I wish instead of boosting the spell to be similar to fire spells, I think each magical school should be more focused on each subject.
What is water? slowing + damage + random stuff.
What is fire? damage + more damage?
At least this one water spell have a prerequisite that is fairly "odd", so its not just plain better than the fire spells, I do think mana cost should be balanced against damage on a more general notice, then meaby fire does it better.
I still wish for some more spells, it would still be fun even if they were all as odd and difficult to use as Tidal Wave.
I might have a different point of view on these spells, but I prefer to have some useful spells, and some spells that come in handy at "just the right time".
Sincerely
~ Kongdej