This build is all about burst damage, speed, and longevity. You should be able to heal through most fights, since you won't be getting hit too much. The bars shown were for single target, but I've included alt's for when you're fighting multiple mobs or opponents.

Bar 1 - Flame Staff

Impale - Your long ranged execute. 'Nuff said.

Destructive Reach/Mass Hysteria - Your CC with solid range. Use this when someone gets too close. Do not spam it, or they'll be immune to the knockback when you really need it. If you're in a dungeon or in a crowded server, switch to Mass Hysteria to hit multiple targets.

Crippling Grasp - Another form of CC with a solid DoT. Slows them down, speeds you up, pretty good recipe for kiting. Use this whenever the effect ends to keep the speed and to frustrate them with roots.

Swallow Soul - Your main spam attack. Decent damage for cheap cost that also grants HoT and a buff that improves the healing from the spell.

Entropy/Power Extraction - Another DoT, HoT, and an invaluable buff. I like it over Power Extraction in most situations because it's long range, and I want to stay at range as much as possible, but like Mass Hysteria switch Power Extraction in when going through dungeons or crowded servers.

Ice Comet - Great burst damage and snare with more DoT at long range. Fits right in with the theme of this build.

Bar 2 - Restoration Staff

Piercing Mark - Reduces their armor, heals you when they die, and keeps them from stealthing away. Perfect.

Dark Cloak - Your escape/re-positioning skill. When you know you can't win, need to get into a different spot for an opening, or need to reset your buffs, this skill is invaluable. With the right combination of CP you can cast this indefinitely. when you need to escape, and it works great in tandem with retreating maneuver.

Harness Magic/Concealed Weapon - Since you're at range and you can handle keeping those stamina builds at range, your main threat are other long range magicka users. This is your ward against them. If you're confident in your survivability you can switch in for Concealed Weapon for more stealthed speed and another CC.

Rapid Regeneration - This adds more survivability with a strong HoT that is even better with Swallow Soul's passive buff. This should keep you healed throughout many 1v1 fights.

Retreating Maneuver/Refreshing Path/Healing Ward - This is to avoid snares and keep your speed up, either when you're stealthed or trying to get away. Try to avoid using it while fighting to save your stamina for breaking free. You can switch it out for Refreshing Path when in confined areas like IC for more HoT, speed, and DoT to them. Healing Ward is good for another solid ward, the only reason I didn't include it initially is because if you want it but you're around another player in your alliance that has less health, they're going to take it. While this could be solved with the other morph, this offers a source of immediate healing that could be useful in more situations. Only use it if you're running solo.

Soul Tether - Another snare, burst damage and HoT. Use this when they're up close and you're in need of more healing.

Champion Points - The big ones are Elemental Expert for the magic damage, Magician for the reduced cost, Arcanist for magicka regeneration, and Quick Recovery to boost the healing. Everything else is up for debate.

Mundus Stone - I like the Apprentice for the boost in spell damage, but the Atronach and Mage are solid for resource management.

Gear - 5 piece Phoenix for the insane survivability. Aw I died... OH WAIT. It's great. Plus the other set bonuses are decent as well. Willpower jewelry of course, as you're a magicka build. You should have one piece Molag Kena for the extra damage, preferably the shoulders so that the helmet can be made heavy for the extra protection and to proc Shadow Barrier. The helmet and staves should be Torug's Pact for even more damage. This altogether ensures more longevity and burst damage.

Race - Breton is the master race for this build for the magicka bonuses. Altmer is decent, but you're not using much elemental damage so they're passives are much less useful.