Here is a video of a nuker who doesn't use any Fire or Cold(Well no Snow Shield) or Weapon skills, Just Lightning Nukes and Shouts.
http://youtube.com/watch?v=AfY67X_cJwA
Basically what I'm saying is. Base your nukers off of Lightning and at least 20 in cold for a level 1 Snow Shield for emergencies. Here are the pros and cons of the possible secondary Masteries to take(Although for now there will be more than 1 if you choose to farm it)
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Max Cold Mastery - SP at 80, 271k with Cold 80 Light 80 and Bicheon 20
Pros - You get a strong spread nuke and a strong physical defense. The Cold buffs and passive at higher levels begin to become stronger than the Cleric buffs and Armor passives. This makes a strong Garment nuker which makes it ideal for both PvE and PvP.
Cons - You miss out on extra damage possibilities and possibilities of damage mixed with defense. I would personally take this one or Sword.
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Max Fire Mastery - SP at 80, 283k with Fire 80 Light 80 and Cold 20
Pros - You become MUCH stronger compared to full lightning nukers. You gain an extra 2-3 nukes to use and a stronger imbue. You get a stronger Magical defense, Invisible/Stealth detect and a Possibility for immunities.
Cons - Only lvl 1 Snow Shield which although isn't that significant is kind of limiting. This also supports Armor a lot more than others which I happen to hate because of the MP problems but that's my personal opinion.
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Max Sword Mastery - SP at 80, 322K with Bicheon 80 Light 80 and Cold 20
Pros - This has the odd possibility for both more damage and defense. It has KD's and Status effects that reduce damage. The 15 sec Buff gives Physical Defense which is good for emergencies. The lvl 100 Combo also has a large possibility for defense vs no immunities because it causes Fear, Dull and Stun. The passive also improves Block Ability and you get a Shield.
Cons - Only lvl 1 Snow Shield which is a little more forgiving with the Shield Buff. It supports the rather ugly Protector armor and KD's can make you somewhat of a sitting duck in large scale PvP. Other than the defense reduction Statuses it does not help you in PvE.
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Max Spear Mastery - SP at 80, 282K with Spear 80 Light 80 and Cold 20
Pros - This has the greatest possibility for a large spike in damage plus a strong ranged attack and Stun + KB. The 15 sec Buff gives Magical Defense which is good for emergencies. Ghost Spear is extremely powerful combined with nukes and Ghost Spear + Soul Spear allow for that "possible" extra defense. The Passive gives an HP Bonus and this also works good on a S/S.
Cons - Only lvl 1 Snow Shield which although isn't that significant is kind of limiting. This also supports the rather ugly Protector armor and you are the weakest overall nuker there is.
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Others...
Max Force Mastery - SP at 80, 256k(W/O Self Heal, 287k W/ It) 80 Light 80 Force and 20 Cold
Pros - A bonus ability to heal, res, cure status ailments, reduce defense and is a VERY strong plvler. The self heal ability helps in emergencies and can help you to survive. The Status Ailments allow for a superior 1v1 ability compared to all others and in Large Scale battles you can heal and res your friends.
Cons - Only lvl 1 Snow Shield which although isn't that significant is kind of limiting. This once again supports the rather ugly Protector armor but overall it is a strong character but not the character for people who are looking to be a nuker the whole time.(As in deal damage and not support)
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Max Bow Mastery - Not even worth doing the SP to...
Pros - For PvE you gain a larger range and probably grind faster than any other character. You gain a boosted attack rating and on a S/S set are better off than a pure Lightning nuker.
Cons - Only lvl 1 Snow Shield which although isn't that significant is kind of limiting. This once again supports the rather ugly Protector armor and until you are able to get your second KB combo at lvl 100 cap skills using a bow in PvP is pointless other than the point as it deals a little more damage than Sword.(You can chain the 2 KB Combos and get the strongest "possible" defense there is but it would be better to just take Force, Sword or Ice)
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My opinion is I hate Chinese Armor and Protector. Don't post about it. Seeing as people didn't bother to read or spread the info for me I'll restate that the max SRO cap is 140 and allows for a lvl 1 Snow Shield at Max Cap. You do not need any stronger of a Snow Shield over 20% or it is just overkill.