Since the number of questions about INT based builds has been rising lately, I figured I would write a guide. I have played a lvl 64 pure INT spear nuker, and a lvl 77 hybrid sword and shield nuker, so I do have a bit of experience with the build.
INT based builds are usually called nukers, because their main attacks consist of the distance attack spells like the Flame Wave Series and the Thunderbolt Force Series. They can be so called pure INT nukers, which means all points go into INT, or hybrids, which means some points are placed into STR to sacrifice some damage power in return for more HP.
HYBRID
If you choose to play a hybrid, remember that your main damage source is still your magical attacks. As such I would put between 20 and 40 points into STR for a sword nuker and between 40 and 60 points into STR for a spear nuker.
WEAPONS
INT based characters use either sword and shield or spear, because these weapons carry more magical damage than the STR based weapons blade and glaive. Bows are usually used by STR based builds as well, since most bow skills are physical, and because bow users rely heavily on the physical based crits. A lot of nukers will use a bow up to level 30 though, since the first nukes become available at level 30.
The choice between sword and shield or spear depends mostly on your playing style. A spear deals more damage, and the shield gives you a better protection, so you receive less damage. A shield also gives you yet another item to increase your INT and STR using the blue stats, and it blocks some of your opponents attacks. If you use a shield, it is important to get one with a high block rate, since the block rate determines the chance that an attack will be blocked. Crits on weapons are of no importance to pure INT builds, and of relatively little use to a hybrid build, so do not spend too much gold on a weapon with a high crit. High magical attack power and magical reinforce however is very important for your weapon.
EQUIPMENT
Since an INT packs less HP than a STR build, and because INT users already get extra magical defence from their INT, most INT builds tend to wear at least protector, and most wear armor. At low level however, the difference between armor and garments is small, so you can safely use garments upto 4th to 6th degree, and switch to armor at some point in your 3X or 4X levels. Try to get a lot of INT, STR, and HP on your equipment. You will need the INT to increase your damage, and the STR and HP to improve your low HP, and for hybrids to improve your physical damage. After level 60, it is not unlikely that about 40 percent of your HP total comes from your equipment.
SKILLS
With the ever increasing level cap and the mastery cap remaining at 300, many nukers now find out they have to start thinking about 2-3 masteries rather than the 4 used upto recently. At level 80 you can afford to have 4 masteries, but you will be doing a LOT of skill deleveling when the 90 and 100 level caps arrive, which will cost you a small fortune. Alternatively, you could focus on 2 or 3 trees from the start, and save yourself a lot of SP farming and skill deleveling.
For your trees, you have the following options. You yourself will have to chose what type of nuker you wish to be.
bicheon - very useful for sword nukers
heuksal - very useful for spear nukers
cold - for physical defence, freezing, wide nukes, and snow shield
lightning - for parry, fast walking, strong nukes, and magical attack bonus
fire - for magical defence, effect immunity, strong nukes, and detecting stealth
I have left out force, since very people are willing to hang on to it with the level cap increases. I am one of the few remaining people that can res level 80 people on Troy.
My personal preferences for strong builds are as followed [take into account that following them at each level cap would require a LOT of skill deleveling].
level 80 cap - bicheon/heuksal 80, cold 60, fire 80, lightning 80
level 90 cap - bicheon/heuksal 90, cold 60, fire 60, lightning 90
level 100 cap - bicheon/heuksal 100, cold 60, fire 40, lightning 100
Why do I drop fire rather than lightning? IMHO, the stronger nukes of fire cannot compensate for the loss of the magical attack increase skill in lightning.
BICHEON
- Smashing Series - NO.
- Chain Sword Attack Series - Nice to have, especially the Lightning Chain that gives bleed, impotent, and diversion is very good. Does more damage than a nuke, but only hits one enemy.
- Shield Technique Series - YES. This short-lived huge increase in physical defence or block rate has saved me many a time.
- Blade Force Series - NO for pure INT, optional for hybrid.
- Hidden Blade Series - YES for hybrid and PvPing pure INT, optional for non-PvPing pure INT.
- Killing Heaven Blade Series - Take it if you take Hidden Blade Series.
- Sword Dance Series - NO for pure INT, optional for hybrid.
- Shield Protection Series - YES.
HEUKSAL
- Annihilating Blade Series - NO.
- Fanning Spear Series - Optional, I do not have a lot of experience with it.
- Heuksal Spear Series - Yes for hybrid, NO for pure INT.
- Soul Departs Series - YES. The stun of this skill is very handy.
- Ghost Spear Attack Series - YES for hybrid, optional for pure INT.
- Chain Spear Attack Series - YES, especially the multi enemy hit of the last chain is nice.
- Flying Dragon Spear Series - Optional for hybrid, NO for pure INT.
- Cheolsam Force Series - YES
COLD
- Cold Force Series - Optional, it is the weakest imbue of all forces, but freezing and frost bite can be handy.
- Frost Guard Series - YES.
- Cold Wave Attack Series - NO.
- Frost Wall Series - NO. Activation is too slow to be really effective.
- Frost Nova Series - YES. Very handy to slow the battle around you down.
- Snow Storm Series - Weak but wide nuke, optional.
- Snow Shield Series - YES. Considering you use a lot of MP for your nukes though, I would not get more than 40 percent for hybrid and 50 percent for pure INT. 30 percent is already very helpful though.
- Cold Armor Series - YES.
LIGHTNING
This tree has no weak skills for nukers. The Thunder Force Series [imbue] is optional if you already have the fire imbue, but other than that ... get them all.
FIRE
- Fire Force Series - YES. This is the strongest imbue.
- Fire Shield Series - YES. This can make you immune to freeze, shock, poison, etc.
- Flame Body Series - Optional for hybrid, NO for pure INT.
- Fire Protection Series - YES.
- Fire Wall Series - NO. Activation is too slow to be really effective.
- Flame Wave Series - YES. These are your nukes.
- Fire Combustion Series - YES. Only useful against players, so if you never job or PvP I guess you can leave it be.
- Flame Devil Force Series - Optional.
taken from the offical sro hp
what is the best for pvp? 
