This is a list of Incar skills and spells, and some info on exactly what they do.

DISCLAIMER:
I included ratings. These are relative to how much they help you in 2Moons. Frankly they're all uncreative boring dross, simply perpetuating the grindfest war-machine that is Korean made "F2P" open-beta MMOs with cash shops.

When will people learn that "open-beta" is just a way to entice players to play?...anyway, on to the meat.

Passives:

Energy Mastery:
3% defense boost per point, maxes at 30% (10/10 pts)
Skill rating: A+

Reasoning:
Defense is huge for Incar, you AoE constantly and get beaten on. This gives you the third highest defense in the game with Seize Nimbus.

Seize Nimbus:
Applies a 3% buff to all non-physical resistances per point spent, for a maximum of 15%. Also increases defense by a value that seems set per rank. Good duration with a 20 second break after it wears off.
Skill Rating: B

Reasoning: The defense buff from this skill is marginal, and the boost to resistances follows suit. It seems elemental resistances are applied after everything else, so a level 60 hitting you with a 1000 damage lightning spell would hit you for 850. It's nice, but it's not necessary.

Mana Force:
Gives you a huge mana regen boost for an extremely low hp cost. Max rank only burns 260 hp, and it gives you quite literally unlimited mana for the duration of the spell, until very high levels (EG: 100+). It has a cooldown 10 seconds longer than the buff duration, so it's pretty much like unlimited mana hacks. This skill is necessary.
Rating: A+

The rest of the passives suck, so I won't get into them.

Fire, Ice, and Lightning:

Mastery:
10 points gives you +15% resistance and +30% elemental damage. If you plan on casting spells of an element, max this out. I recommend getting all three to 10/10 by level 150.
Rating:A+

Ice/Fire/Lightning Bolt:
Ice and Fire bolt are single target elemental shots. Lightning bolt does slightly less damage than fire, but has pierce so it can hit multiple targets. Ice just blows because it does the least damage, and has no effect. I wouldn't put more than a single point into these.
Rating: D

Fireball/Ice Wave/Chain Lightning:
Fireball is a single target spell that does AoE damage around the target. It hits the hardest.
Ice Wave deals the least damage, but slows movement speed by 50% for 4 seconds. I recommend at least one point in this if you plan on killing players.
Chain Lightning is similar to fireball, except that it has pierce and can explode on multiple targets. (EG: 2 enemies standing in a line will each be hit twice by this spell, as opposed to once by fireball)
Rating: Ice Wave: B
Fireball: C
Chain Lightning: B

Fire Blaze:
This is where the three trees start to differ slightly. Fire blaze raises fire directly around your body and can hit up to 3 times. It has absolutely no cast time, and is a great finishing move (run and stand inside the target, then hit this for maximum effect.). For such a low rank spell it is excellent. Also great for busting down doors in dungeons, since they cannot be knocked out of the area of effect damage it deals.
Rating: B+

Ice Spike:
This spell has potential, but it isn't fantastic. It has a chance on hit to freeze the enemy in a block of ice, seems to be approx. 60%. The ~2.5 second cast time makes it rather hard to use, and it isn't guaranteed to work-it can hit and simply do damage, which is low for this rank. Single target spells this far in the tree with this low damage and no guaranteed effect are pretty worthless. Especially for 2.5 seconds of casting. If it hits you can follow it with an AoE spell, then follow that with another Ice Spike if you have someone running in circles...but Ice wave is pathetically better.
Rating: D

Lightning Chase:
This spell is average. Has a short cast time, hits for pretty high damage, and is another ranged (small) AoE spell for your arsenal. Great to follow this up with a chain lightning when leveling early on. However it simply doesn't hold a candle to Fire Blaze, unless you're using it to pull groups of enemies.
Rating: C

Ice Storm/Fire Fury/Lightning Circle:
I thought the trees were becoming more unique! These three spells are IDENTICAL, except that fire does the most base damage, followed by lightning (Which makes no sense, really.). Target someone with this spell, and it drops a rather large, circular AoE over the center of their character model after a ~2.5second cast. Very effective for leveling. Also effective to get all three of these for maximum effect.
Rating: B

Flame Burning/Ice Blanket/Cruelty Lightning:
Once again, three spells all alike in dignity...in fair 2moons where we lay our scene..(Sorry, Shakespearean reference needed). These spells hit one target 6 times with elemental damage. Once again fire is the strongest, followed by lightning and then Ice. The reason for the damage differences is still unknown. Good for Duels/small group pvp. Also good for finishing things off. not that great compared to the three AoEs of yester-tier (Oh, you liked that pun, didn't you?).
Rating: A

Blast Phoenix/Freezing Spirit/Thunder Spear:
Phoenix does tons of damage and teleports you a short distance, great for closing space in a duel or chasing. Freezing Spirit is the first slowing AoE you get, which is great in some situations, but it's not that pro. Lightning spear is great for following Imitid Flash in a duel or otherwise. It does directional damage similar to blast phoenix.
Rating: A

I don't have the final three spells, but I know what they do.

Infernal Pillar: Directional multi-target fire damage, causes a burn effect which diminishes an enemy's hp through their shield in PvP. Knocks the enemy around a bit too.
Rating: A (For damage and functionality)

Gracious Eddy:
This can be pro if you use it well with Freezing Spirit. It's basically a targeted version of Freezing Spirit that hits the enemies around the target. Slows movement and attack speeds by 50% for 4 seconds. Useful if you're having your frail mage-body knocked around by a bagi. Damage on it isn't that great, but it has utility.
Rating: A

Imitid Flash:
Ok, this spell can be insane. It does high aoe damage around the caster in a large radius, and causes a self-buff for 5 seconds which increases lightning damage by 110% for its duration. That more than makes up for the difference between fire and lightning damage, but you can't exactly spam it. It works well in combination with either lightning circle, thunder spear, or cruelty lightning.
Rating: A

Summary: All in all the Incar spells are uncreative and boring. Each tree is a blatant replica of the others, and there are trends that make no sense. Why does fire have the highest base damage, even when similar spells in other trees do EXACTLY the same effect? It's almost nonsensical to get any ice spells that don't have a slow effect, as their damage is so much lower. It seems like whoever put together the abstract plan for Incar spells is brain dead in the right hemisphere, because there is zero creativity here. Every spell is just another nuke.

All Incar spells either...
A: Nuke one guy.
B: Nuke more than one guy.
C: Nuke a guy and slow him.
D: Nuke a guy and make other lightning nukes nuke more.
E: Nuke a guy and move your character slightly.