My own Evoker Guide

At Level 50, you should have these skills.

Brom's Curse - 7
This should be maxed because it is an awesome skill, especially when your in a party and want to keep everyone alive. Along with health injector's you shouldn't have trouble staying alive. This skill allows you to take 14% of your life back every time you hit an enemy at level 7. Although there is a limit, it works every 2 seconds, so you can't use a quick firing weapon to steal your life back extremely fast. But with lightning field it will be hitting lots of enemies at once which will result in you getting a huge % of your life back at once if you are hurt.

Drain Power - 2
pre req for elemental drain. I tend to use a lot of power injectors for this build instead of using this skill. But lots of willpower helps!

Drain Life - 2
pre req for elemental drain. Use health injectors and Brom's curse instead of this. And blink away if those aren't doing enough to keep ya alive.

Elemental Drain - 5
This skill owns, when there is a tough enemy it allows you to do a lot more damage. Also if they are hitting you with lightning or other elementals it will reduce the damage taken by quite a bit.

Concentrate Damage - 10
This skill should be maxed because it comes in handy, especially in groups, but even in solo. What you do is cast this skill, then use spectral lash on an enemy from a distance, if they aren't dead then cast lightning field in front of you and begin to back up. Then when they get closer cast lightning field again and start to use Arc Legion, if they still have some life then use Brom's curse and keep throwing down lightning field and Arc Legion. If the enemies are still hurting you too much, then blink away and repeat.

Dual Focus - 1
You only need one point in this since you are not going to be a tank for this build and will be putting a lot of points into willpower.

Blink - 1
Some people think you need more than one point because of the 20 second cool down. But you shouldn't have to be fleeing in a panic with all the damage being dealt and Brom's curse. You can take away spectral lash mastery or one or two points out of lightning field if you want more into this skill. It will reduce the cool down by a few seconds but i don't recommend it.

Spectral Bolt - 3
pre req for spectral lash.

Spectral Lash - 5
At 30 meters, this is enough. It is good for sniping off flying enemies from a distance especially. It is also good for luring mobs closer to your lightning field and Arc Legion. I don't think it's necessary to put 10 points into this skill and have 45 meters.

Spectral Lash Mastery - 1
It's up to you if you want to put one point in this or not. I do just so that every now and then you can have an explosion that allows you to take less damage and do more damage to the enemies. But since the blast area of it isn't very large i wouldn't suggest dishing out too many points into this.

Lightning Field - 5
This is an absolute must for this build. With it's quick casting time you can be running from enemies and throwing it down. With Brom's curse it makes it even more valuable from all the health you can receive from enemies. Some people don't like to put 5 points into this skill though, so it is up to you how much you invest. Every skill point adds an increased radius for the lightning field, it does not increase damage. I would suggest adding at least 3 points into this skill and no more than 5. It depends how big of a field you want.

Tempest - 3
pre req for Arc Legion.

Arc Legion - 5
This deals huge damage to enemies. Putting 5 points into it allows a 15 meter range which i think is enough. It seems like a waste to put 10 points into this since that only adds 5 more meters. But this is another one that is up for debate. I would suggest sticking with the range of 1-5 points for this skill, it just depends how close you want too be to enemies.

As for stats, you should put the minimum amount of accuracy and strength for your equipment. Then put what you think is necessary for stamina and willpower. If you play solo a lot then you might want to put an even amount of points into stamina and willpower. If you play with groups of people more often then you might want to add more into willpower since you won't be taking as many hits.

P.S. Don't think about skipping out on Brom's curse because you will need it on nightmare difficulty and especially if you are playing elite and/or hardcore.

P.P.S This is one of many many builds for an evoker. There are so many combinations that could be used effectively, but this is what i find to be fun and work. I find that as long as you don't spread out your skill points into too many areas then you will have a decent evoker. Good luck! and please feel free to comment.
FROM: http://hellgate.incgamers.com/forums/showthread.php?t=4637