ok.... decent guide with quite a bit of missing info, in my opinion.
Ice Arrow:: the disadvatage is that it auto targets and that it hits only a few targets, so it's bad for mobs. It's good against the minibosses that move around and attack close up. (stops enemies for short time, for low level. Don't know about higher levels.) Targets only enemies in front of you. Shoots in different directions with no target. Decent range.
Icicle Rain:: Canceled relatively easily by attackers. Up close, it can push enemies back. For enemies that can't be pushed, it hits approximately 3-4 times, more or less. Approx. 7 hits if it is an enemy that's up close. Slows enemies down (status effect)
Ice Barrier:: Enemies will attack it if the enemy is close enough to it. It is an advantage and a disadvantage, depending on the situation and how the wall is used.
Ice Pillar:: Raises enemies off ground, somewhat high. hits 1-3 times, depending on size of the enemy and where the enemy is.
Cold Ice Dragon:: Close range attack, useful for Summon Rock combo.
bitter cold breath:: didn't get the skill yet...
Fire bolt:: no auto target
Fire orb:: has auto target. One target only (I think)
Ocean of fire:: easily canceled by enemies. Burns targets.
Didn't get the other fire skills... level issue... ^-^"
Fury of land:: Slows down enemies for a short while. Does not prevent enemies from attacking. Able to run as soon as you finish casting (I think...) Casts quickly.
Hand of Earth:: I personally don't use it, but you NEED it if you are soloing stages. one of the Chapter 2 stages needs it...
Summon Rock:: Canceled easily be enemies if they are close. Canceled by walls occasionally. Depends on which stage.
Land Giants Fist:: 1-3 hits depending on where the enemy is. Not very useful for combos (in my opinion), except for finishing one or for very short/small combos. Knocks enemy away, also lifts enemies off the ground.
Other earth skills either already listed or I haven't gotten them
I don't use bless skills, so.... no data on them... Don't know how useful they are anyways....
Mana Recovery:: somewhat useless, unless you can't use your charging skill... Recover more mana (NOTE:: MORE, not FASTER)
Mana Increase:: More mana to spam skills without having to charge as often.
Deadly Magic Blow:: Not very useful, though you do get some extra damage on the enemy... probably not THAT much more though...
Concentration:: More skills for the amount of mana you have. I think you recover mana faster as well...
Health Increase:: Already stated previously, though you don't NEED it if you are skilled at dodging. No, I mean VERY skilled at dodging.... (Rock section at 1-1 Legend, very important.)