IMO:
Rock dude:
Smashing Sword is good early but useless later.
Rockwall is pretty useless (others disagree)
Rockfall is horrible.
Underground Blades are excellent when upgraded properly.
I use the first and last a fair bit but ignore the other two.
Sleem:
Poison Spit is useless.
Evil Shoal is extremely good early on, but weak later.
Cloud of Poison is pretty bad.
Glot's Armour can be useful at times.
Evil Shoal is essential early on but Sleem isn't so hot later in the game.
Lina:
Chargers are really, really stupid.
Gizmo can be useful, but ultimately is quite weak.
Ice Ball can be devastating if used correctly (from long distance).
Ice Field or whatever it's called is crap.
In general I use Lina the least.
Reaper:
Soul Drain is THE BEST RAGE SPELL. PERIOD.
Rage Drain is nice, but it interferes with Soul Drain so I don't use it much (unless there are no souls to drain).
Time Back I haven't learned to use properly.
Black Hole seems great initially, but it uses so much rage and you get it so late that you will be facing huge stacks in the later part of the game, so it isn't as good as it seems.
Reaper is the best.
My order of preference by level 20 or so:
Soul Drain
Underground Blades
Ice Ball
Rage Drain
Glot's Armour
Smashing Sword
Evil Shoal
and that's all I use.
