Update: Mostly just acquired some new Set pieces to increase my Damage, and Mitigation, but I'm also going to re-write it for Clarity
This is mostly about Passives, so unlike most of my Builds, it only really works with 1 Race, Class, and Weapon:
Also has bonus to Destruction Staff XP, and All skills leveling, so this makes it easier to train up from the beginning. (Rather than respeccing a particular Character.) However, the Spell Recharge Passive also has a flat 5% Damage Reduction while Channeling an Ability. This goes up to 20% wearing Robes of the Light of Cyrodiil (Aldmeri Dominion)
Storm Calling with Lightning Staff for DPS, takes advantage of 2 more Percentile based buffs: Ancient Knowledge, and Expert Mage both increase the Damage of any spells that are Lightning Based AoEs, so her front bar is All of them. (The former gives you an 8% Damage Increase to AoEs with a Lightning Staff out, and the latter deals an extra 2% to Shock (And Physical) Damage for every Sorcerer Ability slotted. Right now, that's at 8% It could go as high as 12% if you don't use any Destruction Staff Abilities, but I do.)
Her back bar, honestly isn't all that important, because she only really needs to swap when she starts to take too much damage, and fears for her life, but honestly she Tanks, because I'm a tank at heart, and I just get bored running the same rotation over, and over again. So, use whatever you want, if you can come up with a Single target Fire Staff bar that does more DPS than ^That one to a single target? Use it, because I haven't yet.
 Boundless Storm: Major Resolve, and Major Ward for 22 Seconds, as well as a 5 meter Radius of Shock Damage centered on you. (Also, 4 seconds of Major Expedition, which I like.)
 Blockade of Storms: Another AoE out front, which can set Concussed Enemies (Form Power Attacks) Off Balance. I don't really use that last part, but it's there, and it happens from time to time.
 Impulse: My Spammable, basically so I don't have to Aim. This spec is for standing in the middle of everything, not unlike a Tank, only the idea is to Kill them, not take Attention away from the Healer. She's "Tanky" enough to survive, usually. Sometimes I get overconfident, and pat the price, but this is the basic equivalent of Steel Tornado on a "Spin to Win" Spamina build: Something that i don't have to wait to recast, there's no cool-down, I basically just spam it when I'm not re-upping one of the other spells, or Channeling a Power Attack for more Magicka.
 Liquid Lightning: Your choice on which Morph to pick on this one, I like the more compact radius, because it fits in with Boundless Storm, and Impulse (You don't want mobs inside 1 AoE, but outside another. Move around so more mobs get Hit, but the main thing is using Aggro to keep them inside the Radius of Liquid Lightning. Since that's the second longest Duration (About half as long as Boundless Storm) and the tightest radius. It also costs a lot to recast.
 Is a flex slot, but I mostly use Endless Fury, so I don't have to toggle off the Lightning Staff bonus (8% DPS) to finish off anyone who's low with splash. (And magicka return, which only makes it Spammable with enough targets that are low enough to Kill with it.) I also sometimes use Critical Surge when there's enough targets to make it a reliable source of Healing (My Spell Critical isn't that high, so "Enough" means a lot of them.) I run around Craglorn with my Clanfear "Stompy" mostly for Company, but he also comes through with Heals, takes Aggro, gets some licks in, and Rebates some Magicka when I bar swap. Shattering Prison can hold mobs in the AoE but it doesn't deal much damage, and it's not Shock Damage. It's a Sorcerer ability, so it contributes 4% to my overall damage on the Lightning Staff, but doesn't benefit from it, and the healing from Blood Magic (8% of Max Health, on a 64 Magicka Altmer) isn't enough for the casting cost. Bound Armaments isn't actually all that worth it, because:
Ultimate: Energy Overload is Cheat Mode, I basically save up for Bosses, because this isn't a Single target spec with Best in Slot Sustain. That's for the Back Bar, which you can switch to once you toggle on Energy Overload, but basically what it does is turn your tapattacks into Power Attacks, which give you Magicka back. So, it's Spammable, Lightning Damage, and if the Boss drops Adds, you can hold down the Attack Button for Force Lightning (AoE, and Shock damage, plus it triggers the Damage Reduction from being an Altmer.)
However, this burns up Ultimate, a lot of it, so you want to use it sparingly, when it's needed. it comes out more Efficient in the end, because most Cast Ultimates use up all of it, regardless of Cost. Energy overload allows you to Save it up, for when you need to go into God Mode, but when it runs out, you have to go back to your Rotation with Power Attacks to sustain. (If the fight isn't already over.)
Honestly, I don't use this Hold Down The Win Button because it takes all the fun out of the fight, but if I have to, I can burn up all of my Ultimate for a full Magicka bar, and then go back to my regular rotation. (Which makes combat boring enough as it is.)
I tried a bunch of stuff, but TBPH, I got used to Tanking from playing every Race/Class combination I could think of since the last major global changes, and I just got used to fighting this way. It's Muscle memeory, if I forget my rotation, or the plan goes to fut, I can fall back on this, and just react with the tools at hand:
Streak: This is pretty much just for getting around the Map, and to the next Dungeon/Fight quickly. Yeah, it does Shock Damage in an AoE, but not enough to have it on the Lightning Staff side, which is full of Shock Damage AoE. (The 12% bonus isn't enough to make it a DPS spell, and it's not Spammable, because you move every time you cast it.) However, since it doesn't require a Target, you can skip gaps, and obsticles, like Traps, Lava, and chasms. The Stun can also get you out of trouble, but it doesn't last.
 Shielded Charge: This is another Mobilizer like Streak, but the difference is that it IS Spammable, and the Stun lasts long enough to actually be useful. I like feats that give you at least 3 Effects for your Stamina Cost, especially on a Magicka spec that has to stop to generate more Stamina. "Get Back Here!" Stun, and a damage shield that might break in seconds, but if I'm taking that kind of beating (Through Block) I handing out Stuns like they're candy, anyway.
 Pierce Armor: About the only other thing I use Spamina for, Major Breach, and Fracture, with a Taunt. I don't mind the taunt, the other bar is set up so the worst place for them to be is within 5 meters of my Staff, and I'm just about Tanky enough to survive the fight. I'm not Tanky enough to take over Tanking if the Tankety-Tank TANK dies, but what I can do is Kite the baddies away, while he Rezes, and we can reset the fight. The alternative is a Wipe, and start over from scratch, with damaged Armor. Not a great alternative. So, In that case (Just Encase for playing DPS for a tank) I Root them, Streak in for Stun (Root, and Stun can stack) Pass out taunts with Major Breach and Fracture, then Streak out on Magicka. Agin, I don't have a lot of Spammina, and I deal negligible damage with it, but I can take the Agro, and Kit long enough for the tank to burn a Soul gem, and the Healer to get him back up to full Health. The alternative is a Team Wipe, then we all come back with less armor!
 Dark DEAL. I know, that's the "Wrong" morph, but I got my Magicka bar dialed in so that I don't have to stop DPSing to channel more Magicka. Now that i've got 5 piece Robes of Cyrodiil's Light, I take 20% less damage when Channeling. (Power Attacks too, and that includes the Lighting AoE that is Energy Overload!)
 Again, you can also use this as a bit of a flex-slot. I put in Absorb Magic, or Bound Armaments, which is great that you don't have to duplicate like a pet. (You used to, but you didn't get Pet bonuses from it, like the Necropotence set.) Also Encase (Just Encase) if i have to support a Tank who might die, and need the Agro kited away, or I just want to hold a Bottleneck with Blockade of Storms, and Energy Overload. "Un, Limited. POWER!" Well, not quite, but Ultimate can pile up if you do really need to use it, and sometimes it's fun to just Pull them through the door, and roast them on the spot. Silver Leash, and inner Fire, of course. If I'm Seriously tanking, Serious content, but that means replacing my Robes with some Serious Armor. (Almost a complete respec, she has to stop by The Lady for her Boon. Oh yeah, The Thief for Critical Surge.)
[R] Suppression Field: Lockdown. There's so many Boss Fights, where we have plenty of DPS, but the mechanics include a lot of Spells. (Honestly, these aren't usually Single Bosses, but the Big Bad has Menders with him to heal him, and basically make your job a lot harder.) So, shut up, Mages. Otherwise, Aggressive Warhorn if I slip into something a lot less comfortable to respec into a TANK.
One of the nice things about this one, as far as playing it is I basically don't have to worry about Barswap cancellation. Most of what I need is on the Front Bar, so I spend most of the fight there, and all of the Durations are easy to see when one goes down. (There's a little Overlap between Liquid lightning, and Blockade of Storms, but the latter is so much Larger an area, and the former has the big ball O lightning in the middle. Can't miss it!)
So, the starting rotation, after barwapping for any Prep (Like picking 1 to Die first with Endless Fury. Typically the Healer. Possibly Encase just to make everything hold still while we get in position, but usually Critical Surge for Healing) is basically [4, 1, 2, 3...] Weave in Attacks as needed, but you don't need to Power Attack at first, because you have a full bar. You want the Liquid Lightning down first, then the Blockade, because it lasts just a little under twice as long. So, by the time you re-cast LL, and cycle through again, it's just about time to cast both the next time around.
5, and 1 (Dark Conversion, and Endless Fury, respectively) are both reaction Casts, depending on the situation. BS adds a little DPS around you, but not compared to Impulse. It's more Efficient however, and there's the Major Resistances it grants. Fortunately, it lasts a Long time, but if I'm not taking Damage (Because the tank is doing his job that well) or trying to catch up with the group (Unlikely with Streak, but I sometimes have to take a break and channel Stamina to recover from Sprinting) it's better to save the Magicka for something that does more damage, like Impulse.
Another point where I barswap cancel is to re-up Critical Surge. I don't always need it, either for the boost in Spll Damage, nor for the Heals, but when i do, it's slotted on the back-bar so that I can just spend as little time off the lightning Staff (And it's 8% bonus to all that AoE damage ticking away) as possible.
4+1 Infused Lighting Staff of Torug's Pact is me go-to Crafted set, because it stacks on the Infused trait on my Staff (Of Torug's Pact,) and the other 3 bonuses don't hurt on my back bar. More health? I'm an Altmer, of course I always need that. More Spell Resistance doesn't hurt (Me) and Spell Damage? Yes please! Also, I honestly have about as much patience as it takes to farm 1x5 piece of any set. "Blame it on my ADD, baby!" I always use at least 1 Crafted set, on any build, so that whatever 5 pieces I don't have used up by my other sets, I can make them. Magicka, and a Shock Damage Glyph. Obviously, otherwise Divines all around so I can switch from Spell penetration to Spell Critical if I need to. I happen to be on The Thief right now.
3+2 Order of Diagna. Sword, and Buckler, Necklace, and 2 rings, I use on pretty much ever build now, because it's becoming my favorite set! Max Health, Max Heal (3 piece jewelry) Then Healing Received, and Minor Vitality when I'm channeling Dark Deal. Also, I couldn't get the Sword in Defending, but I could Enchant it with an Absorb Stamina glyph, and put a Max Stamina glyph (From the Fighter's Guild) on the Shield. It ain't much, but it's better than nothing, again I'm an Altmer here, but she never has to Tank for very long, unless she's doing it just for fun, because she can.
So anyway, I assume either 1: You don't have the Best in Slot sets, or B: You know which sets are Best in Slot. Either way, I don't have to tell you, my guides are for the players who haven't beaten everything, in record time, and became Emperor with Volendrung, and the Chaos Ball at the same time, because they're just that good. They don't need my advice.
Necropotence is my Go-To drop-set for Magicka specs, because it has Max Magicka. All the Max Magicka, even if you're not a Sorcerer (Warden, or Necromancer...) the 2 piece Bonus stacks on the 3 piece, and 4 piece bonus. With Staff, Sword, and Shield, you have 8 pieces of Apparel (Including the Shield) 2 Weapons, and 3 Jewelry Slots. My (Infused) Lightning Staff of Torug's pact fills out the 4 piece set, so the Shock Glyph goes off more often, and hits harder to proc extra DPS. Besides that, you always want more Magicka, that's your bread and butter, all the Magicka you can get if you're a 64 point Magicka Spec, otherwise you would have spent a point or 2 on something else.
This is one of the things I gain from bar-swap toggling between sets, and having a Shield on a Magicka Sorcerer: 2 empty slots for more set bonus of Necropo, and another stack of Max Magicka. If it was another Staff, let's say the Restoration Staff of necropotence I have gathering dust in my bank, because Healer in ESO sucks, then at most, I could get a 3xbonus, but I have a couple spare slots open (On my shoulders) because I haven't played the Trophy Chest lottery long enough to get the Monster Helm, and Shoulder to go with it.