First of all, and perhaps the most boring for some of you, the math involved.
Levels 70-120 provides you with a total of 151 skill points, including the given you receive when you achieve mage. Unfortunately, maxing every skill requires 180 skill points. If you've read the title and have been paying close attention, you can kinda guess what skills I'm most likely to drop. Moving on.
The skills and their advantages:
Partial Resistance: At max this eliminates 70% of damage from ice and lightning attacks permanently.
Element Amplification: At max this gives you a 35% boost in your magic attack, but all magic takes twice as much mp. Permanently. Preferable for high levels.
Ice Strike: At max this does 90 base damage compared to, say, thunderbolt's 60, and with much more range. Also freezes. Takes 21 start, 50 at max.
Thunder Spear: At max this does 170 base damage compared to cold beam's 100. Takes 10 start, 24 (same as cold beam) at max.
Seal: At max this prevents nearby monsters from attacking for 20 seconds, 95% of the time. Takes 12 start, 30 at max.
Magic Booster: At max this increases casting speed by 2 for 200 seconds. Takes 58 hp and 53 mp at start, 30 hp and 25 mp at max.
Magic Composition: At max this does 140 base damage, and freezes for 2 seconds. Combines both elements. Takes 14 start, 22 at max.
Element Amplification, Ice Strike, Thunder Spear, and Magic Composition all take 30 skill points to max, all others need 20.
You're a Ice/Lighting mage, meaning you almost surely have the blessing that is thunderbolt, the multi-shot attack; thus you should definitely have ice strike as it brings that style of attack to a whole new level. Magic composition is a necessity as well, as upon its ninth skill point it surpasses cold beam in power. If you do not want to be left in the dust, I strongly suggest you max magic booster, as the new attacks are a bit slower to cast, and the speed will always be helpful. Element Amplification does help a lot, and the fact that it increases by percents mean it will be helpful in all later levels. It is best saved for post 100 levels though, as the double consumption can be very taxing. Seal is great, as a lot of high level monsters do more than touch damage, and 20 seconds to just wail on them is definitely a good thing, even if it doesn't work on bosses. As to my knowledge, there are less than ten elemental attacks in Maplestory, and ice and lightning monsters have a constant protection from our attacks. Partial resistance is basically the same thing, and thus opens to ice/lightning mages a whole new brand of monsters that we hold something over, and no matter how you look at it, being 70% immune to ice and lightning attacks forever rocks. Thunder Spear's real advantage lies in the fact that it does the most damage of any attack, and monsters that are weak against lightning just evaporate in front of it. But that's really it. It only hits one enemy at a time, lasts a tenth as long as seal does, and consumes 30 skill points. Besides, how many monsters out there are weak against lightning? 15, and if you plan on fighting something stronger than a clang, then you can cross eight of those off. If you were to max this, the twice as fast magic composition, the omnipotent ice strike, and the great boost given by element amplification, then you would have to sacrifice 9 points from one of the other, and far more useful, skills.
Here is my skill build:
70: 1 Ice Strike/Magic Composition
71-80: 29 Ice Strike/Magic Composition, 1 Element Amplification
81: 2 Element Amplification, 1 Magic Booster
82-88: 19 Magic Booster, 2 Seal
89-94: 18 Seal
95-104: 30 Ice Strike/Magic Composition
105-113: 27 Element Amplification
114-120: 20 Partial Resistance, 1 Thunder Spear
See, I'm not such a bad guy as to not let you have thunder spear, am I?
Okay, now I'm going to break down the order. I put an attack first just so you can quickly ascend to a much higher level of ownage right away. Really, that's important. Magic booster, which requires 3 element amplification, is next in order to help develop the speed that 3rd advanced maplers are known for, and to cut back on damage received from enemies over time. Seal's next, mostly because you will doing a lot of PQs right about now, and also because this helps training and drastically cuts back attack damage from monsters that you can defeat in 20 seconds, with magic booster. Now is finally the time to max you're other attack, because now is the time to enjoy all the damage you will be able to do right from the start. As a side note, I didn't put magic booster and seal first so that now you have a super awesome attack right out of the box, because that would be intentionally delaying your fun, but because they are critical to fighting all the new monsters that you will encounter on all the party quests you plan to do and dungeons you plan to explore. By now your max mp should be able to fully take the strain of element amplification, so put it now and watch your attacks spiral upward. As I before explained, I don't hold with leveling thunder spear, and partial resistance does have clear advantages that transcend any illusion you may have that you will never, ever fight ice or lightning monsters (because that's just silly) and also blow away the barrier that separates you from fighting these monsters head on. When that's all said and down, you now have a single point left over, and only one skill not maxed. So why not just put it in?
Thanks to XtraBlaze for this next snippet of perspective. It's true that if you level magic booster to 11 you do gain maximum advantage of the skill, but during a shorter amount of time(110 seconds instead of 200). If you are experiencing some frustration or lack of patience by the time you level magic booster to 11, and do not mind the 90 second difference, then I suggest you take this option.
Thanks to TheEnd for the following advice. Partial resistance, at the very first point, gives you 23% resistance to ice and lightning attacks. Knowing this, I advise that you do add a single point, not your first since by level 70 you probably want something cooler, but that you add one early on. Maybe after the first level up.
Thanks to Bodom for inspiring me to add in this next, and quite important perspective on leveling a mage. While many of the guides that I have seen space out some skills, such as seal, I do not agree with that manner of technique(although that is strictly my opinion and is only an advisory consideration). If you've read the two paragraphs above then you may be lead to believe that I am now contradicting myself, but please bear with me. I admit the advantage of leveling magic booster halfway, because magic booster will not get stronger afterward. I also concede that an early point in partial resistance would be a point well spent, because the difference it makes is rather substantial and it allows an advantage early on that my above plan does not provide till the final few levels. However, that cannot be said for any of the other techniques. The three attacks need to be properly leveled to become the truly useful skills they can be, and leveling partway may improve upon your previous attacks, but will cause you to have to slowly gain an edge over various levels instead of seizing power right away. The other skills are all active skills, meaning they all require you to activate them(except for element amplification, which should be leveled when your max mp is large enough and the sacrifice of other possible skills is minimal). Because they are active, they all require a different button. In my opinion, this is not to your advantage. Having a lot of skills does not translate to efficient or effectiveness if the skills haven't been matured. Being a jack of all trades means you have to divide your time between all of your skills, slowly advancing them, and dealing unnecessarily with very short bursts of power to you have to constantly renew. I believe it is far better to master a skill, both with points and practice, one at a time, then to multi-task and get take forever getting anywhere. I apologize to Bodom if this seems like a challenge to his ideals, as I only wished to express my opinion (as it is my guide to everyone else) and to provide my viewpoint on everything mage. Honestly, though, I wouldn't have thought to bring this up without his advice, so thanks to Bodom. Finally, I would like to once again say that this is entirely my opinion, and if you really want your character to advance this way, it's your choice.
And a very special thanks to Bellatrixa. I was not aware that magic composition was that much faster than thunder spear, which is enough to make it much more important. I would have submitted a bad guide if it wasn't for you. Thanks a lot.
Here's an altered skill build that is the culmination of my own preferred method, and the ideas of the four mentioned above. Take note, I still prefer the first skill build as far as magic booster goes. I really appreciate being able to concentrate without renewing it. I do love the partial resistance idea, though.
70: 1 Ice Strike/Magic Composition
71: 1 Partial Resistence, 2 Ice Strike/Magic Composition
80: 27 Ice Strike/Magic Composition
81: 3 Element Amplification
85: 11 Magic Booster, 1 Seal
92: 19 Seal, 2 Ice Strike/Magic Composition
102: 8 Ice Strike/Magic Composition, 2 Element Amplification
111: 25 Element Amplification, 2 Partial Resistance
117: 17 Partial Resistance, 1 Magic Booster
120: 8 Magic Booster, 1 Thunder Spear
Thanks, all credit not given previously goes to me on this, and all I ask is that you please credit Tenz from the MapleTip Forums if you want any part of this. Although you do not have to if you do not want to, as long as you know that are a filthy, filthy liar when you claim the credit for it. Don't e-mail me! I won't ever answer. Ever!
Edited by Tenz, 20 November 2008 - 09:06 PM.