Conjurer is the mage/caster class of Ether Saga. Their attacks are magic based a thus highly effected by INT. As a caster they wear lighter armor and have lower DEF than other classes(exception Mystic).

1) Builds
Pyra/Unda
This is the most commonly found build for conjurer. This is because the 2 most prominant types of skills that Conjurers get are Pyra and Unda. So what does this do? Pyra increase INT +3 for every point, it also makes the use of pyra skills more effective. Unda increases maximum HP+20 and makes the use of Unda skills more effective. With this build you will naturally deal higher damage with the skills you have and also have higher natural HP than other builds.
Pyra/Widu
This would be the 2nd most common build. This build sacrafices the HP from Unda to invest in Widu. Widu increase you int by +1 and also increases your dodge. At lv 42 I dodge about 25% of hits by monsters. While this build is great for PvM I have heard that Widu is far less effective in PvP play. If you plan on PvP’ing you might want to consider a Pyra/Unda build.

Do keep in mind that there is not set build in Ether Saga, there are advantages for most builds. Since equipment makes such a huge impact on overall sucess, you can replace much of the damage,DEF or HP lost from trying an alternative build.

2) Advantages
The ability to drop powerful AOE spells. Many quests require killing large amount of monsters. The ability to use Area of Effect spells well allows a Conjurer to round up large groups of monsters, sometimes levels higher and kill them as a group.
Kiting is another important technique used by mages. A mage keeps distance between him/her and the mob. Casting quick spells that hit the target and allow the mage to keep moving to avoid damge. This technique will help you solo many monsters in instances and can be used to solo monsters much higher lv than you.

3) Equipment
There are 2 types of equipment in Ether Saga. The first is equipment that increases health, these pieces are dropped from monsters in the game world. By imbuing these armor(add +’s to equipment through the blacksmith) your total HP will increase. This is very important to mages that need a larger HP pool(pyra/Widu or non Unda Conjurers). The second type is equipment that increase DEF, these are dropped in instances. The damage reduction from increased DEF is very important to mages that dont have any DEF advantages(Pyra/Unda).
Conjurer weapons when imbued increase int, which ofcourse increases overall spell casting.

4) Socketing options (adding gems to weapons to increase different aspects)
Fog: Increases INT, this is the most commonly used gem for most classes. Since INT directly effects spell casting, most conjurors go for the big numbers.
Rain: Improves strength, unless you are some incredibly ineresting build…I would not suggest this.
Earth:Improves DEF, this is a viable option for mages that solo. The downside of this is that the increase is rather small comared to embueing def equipment.
Water:Improves dodge, this also might be a vaible option. The increase of resistance is small, however small amount of resistance do make an impact. This might complement a Widu build for extra dodge.
Air:Improves mana, the mana gain is small considering mages have a large mana pool. I don’t see any real need for this. If there was a large increase in say mana regen it might be worth a second look.

5) AOE
One of the major advantages of a conjurer is the effective use of AOE(Area of Effect). The first AOE spell available to a conjurer is "Shiver Gust". One thing to know about Shiver Gust is that you WILL NOT get this normally. This is a skill that has to be crafted by a player or purchased through a player run shop.
How AOE works! A player gets a mob to focus on them and then does that for other mobs. Getting a number of monsters chasing them. As the player runs from the mobs he/she will cast an AOE spell like "shiver Gust" to hit as many as possible(refered to as kiting..thx Hualan and Iran).
The standard technique I use for AOE is to run them in a circle. The more you do this the easier and more effecient it gets. When first learning AOE, test how far you can pull your mobs without them running back to where they started. You will get a good feel on what you can or cannot do. Occasionally you might need to cross through the group to keep them in a tight ball or to change their direction all together. Be sure to be able to heal if you HP drops(on mages is does so fast usually).
Practice makes perfect!

Credits go to Bael.