Hello, I am looking for the best DPS build for a dark elf who uses magic type skills
I have seen you're fire DPS build but it might not be viable enough.
I just need to hit the cap of the damage 
But my switch in skills needs to make it so I am also good with a group like for instance in dungeons with more people and in PVP
Can you make something for me? 
Irons is right, the problem with that fire build is that you need to get close for it to be effective. This might not be a problem in most PVE situations (where you're expected to have an enemy on you anyway, since the tank's only meant to hold the aggro of one-two enemies) but in PVP you really want distance from your opponents as a caster. There are several abilities you can use on a DK to become very tanky though, so if you are using a Destro Staff for DPS and then you switch to a resto staff you can heal pretty well and tank quite a lot of damage.
If you like more utility then be a mage, if you like more heals then be a templar, if you like more subtlety then be a NB, if you like more direct damage/heals and active tanking with passive recovery then DK is good. It all depends on what you plan on doing with your character to determine what's the best min/maxed. DK will be best for max DPS, you won't be able to get best PVP build at the same time as best PVE build no matter how hard you try so I'd recommend just sticking to one or the other and then fiddling with the others.
I am being a templar for several reasons, one of them is because I will be very effective with both of my weapons--being able to completely change my roll without sacrificing (much) performance in one or the other. It's the only build that seems effective in pretty much any situation.
You said you just want to cap damage though, so I'd really be a DK firemage. Your group will love how fast things die when you're around, in PVP you'll still do massive damage and then be able to take quite a lot of hits as well when you bar swap.. But remember you will need to be close to the targets.
It might not be that useful in PvE but in Pvp invisibility is one of the best possible skills you can have.The mage light only shows stealthed people with in range so you just have to use range attacks to negate the mage light.Inivisibily is one of the best survival skills because with it you can get away from all attacks, yes you take dmg from AoEs but no one can attack you directly. Even the toughest tank will go down when enough people target fire him but a NB can get away with stealth.
Stealth might be good for entering combat more effectively and avoiding combat altogether. But, you won't be able to stay invisible long during combat and unless you Ult for like..12s or w/e it is..you won't really be able to get away during 2.5s of Invisibility with that re-stealth skill. That's like saying you could uppercut (2h) someone for a 3.5s stun and then run away to restealth? It's not going to go like that. Stealth will only act as a temporary shield against direct damage, a costly one at that for casters because it takes away magicka regen on top of the cost to cast. Yes, you can recast that invisibility a few times.. 5 seconds, 7.5s, 10s, it will add up and you'll be able to get away but Nightblades aren't really "bursty" so the opponent will probably heal during that time and you'll be stuck with no magicka and no kill. Spamming Bolt Escape would be faster and maybe more magicka efficient even to get away than stealth, if we run about 15 meters per 2.5 seconds (which seems about right, just a tad slow) but it'll be instant and depending on the mechanics of the Bolt then it could be even more awesome for several reasons..plus it stuns. Several other examples as well.
And, depending on the effective range on Mage-Light, Stealth might not even be good for avoiding combat in general. I know I'll be rocking the mage-light no matter what, since it increases spell power too.
I just think that there are a lot better abilities than stealth for the same purposes, but they all have more in combat utility than stealth does.
Immediate Edit: I think that stealth/invisibility is good for Melee characters to close distances on Casters. If we were talking about melee-ranged characters then I actually love the idea of stealth for OFFENSE, but not so much for defense still. Yes, it's really good but I think there are better defensive abilities even for melee as well as better escape abilities for everyone.