I have never completed the MQ as a mage nor played the game from start to "finish" on legendary, but I plan to rectify that by playing the most pivotal mage class in Tamriel's history, the battlemage. However, while taking some inspiration from the battlemage classes in Morrowind and Oblivion, I'm basing this character Haldyn from Rise in the East. My reasoning behind this is if I had took my inspiration from Morrowind and Oblivion, my character would almost be carbon copy of a spellsword and a sorceror. Thus for my build I'm forgoing using any weapon that isn't a staff. Note I'm nowhere near done the build, I'm still debating on how I'm going to allocate my stats.

Setting:

1. Legendary

2. Dead is dead

3. Xbox 360

Character:

Name - ?

Race - Nord

Gender - Male

Guardian Stone: Lord

Stat Allocation: I'm thinking of either one magicka for every one health or six magicka for every four health

Skills - Destruction, Alteration, Conjuration, Enchanting, and Heavy Armor

Perks - http://skyrimcalculator.com/353486

Take the necromage perk in restoration for the bonuses you get against the undead, take intense flames and deep freeze in destruction. If you plan on using any of the bound weapons, take mystic binding. Also take quiet casting in the illusion, along with aspect of terror for the +10% to all your fire spells.

My own opinion, is in conjuration, just take the novice to master, and my opinion, I have no use for alteration. In alteration you also do not need stability, for you are not using flesh spells, and you do not need dual casting. In heavy armor, just take one in juggernaut, and go to conditioning. I would also invest in alchemy.

The heavy armor will help you, and in the beginning I would use the mage stone, and put all my points into magicka. When you get up a ways where you feel your character is ready, then switch to a 1 on 1, 1 health and 1 magicka.

Not using restoration, rather not have to chase people down and I could just use the freeze shout, and not using bound weapons.

Having stronger and longer summoned creatures is vital, even more so when I can have two of them. I'm using flesh spells and using dual cast makes them last longer. Only one point in juggernaut isn't enough.

I disagree with the bolded points. If he or she is playing a mage they'll probably have access to the full Slow Time Shout. With the Stability perk Slow Time lasts a whopping [updated] 32 seconds. Extremely valuable for a mage; even an armored one. I see where you're going with the Conditioning on Heavy Armor (mobility over protection), but if the OP isn't using Flesh spells on Legendary (per your suggestion) they might want to invest at least 3 perks into Juggernaut.

Everybody plays differently. I have been playing as a mage since the release of Skyrim. I do not wear armor, as my gal is a pure mage. She wears cloth robes and such that she enchants. I play on adept though, and that is good enough for me. I tried alteration, and do not like it, and will not use it. My opinion. I have never put points into health and never will. I do not need them there, but do need them in the magicka pool. I use no weapons except once in a while the bound ones, and I have no followers, for I have conjuration. I do not use any perks in conjuration except the main ones, for conjuration levels up faster and I have no need for 2 helpers at one time.

Like I said, each person plays differently. I only gave my opinion. No dis-respect to anyone.

Alteration is useful for the perks alone, much less the flesh spells....especially on legendary. I get what you are saying about magicka....you will need as much as you can get early on if you are using destruction for damage.

I'm going to need some health due to playing on legendary.

You will, but not as much early as magicka. With conjuration to draw enemies away you shouldn't be taking many hits. Until enemies start scaling you don't really need much health. Destruction is your main damage source, right?

I'm currently running a pure mage on legendary conjuration, alteration, destruction, enchanting. Also DiD....early on the extra magicka helped