Thx for taking the time to write this mate appreciate it and I was actually thinking about trying ghastly buff drink next to hhhh take its the same as lave with the attributes 25 health 39 mag?I run high magicka on my warden in CP, e.g. 50K+. It's a pure stat-based build using just Alfiq, Necropotence, Wild Hunt and 1x Domihaus. Slot Inner Light, Dampen Magic and a Siphoning skill. This approach definitely works for magicka builds in general and magblade at least has the +8% magicka passive from Siphoning.
I know other people who build for spell damage, in which case you probably want War Maiden with a Stygian back bar and possibly a Master's destro front bar as well as - I'm guessing - Simmering Frenzy. I don't play this, but Elemental Weapon into Clench is a fairly powerful opener and your spectral bow should hit hard. I don't know what defense is like on this kind of build. Probably bad.
Then there are proc builds. Some people use Kjalnar and, aside from the guy in the other thread we both participated in, Blobsky - a long-standing EU magblade main - put up a YouTube video fairly recently with such a build.
For my own part, I'm a frustrated stamina player who likes a fast, close up visceral playstyle, but also loves magblade's ability to perma-cloak. I move around in cloak by default. Concealed Weapon + Wild Hunt + Swift puts your speed on par with dodge-rolling bow stamina builds. My objective has been to make that playstyle work on a magblade. My current build is here:
https://en.uesp.net/wiki/Special:EsoBuildData?id=269881
My first priority, dating back to when I was a PvP noob, was always perma-cloak sustain. I have to break even with my magicka during cloak and, these days, have the magicka to cast cast RAT in cloak as well. There is just so much freedom that comes with that. You're always at full speed. You can always bypass NPC guards completely. You never have to wait to recoup your magicka. It's kind of a short-attention-span playstyle as well as an opportunistic one. I sacrifice attack power for this, but I'm typically in the right place and ready when an opponent is low health.
In order to sustain cloak outside of combat you need to pay attention to your idle magicka regen and cloak skill cost, which is not the same as in-combat regen. I've written about this before. TL;DR: This is why I'm a Breton, am using cost reduction enchants - not magicka recovery, am wearing 6x light armor, using a high-regen drink (Ghastly), am slotting Barrier on the back bar and am using Siphoning Attacks.
I have experimented with Eternal Hunt and Hissmir Fisheye Rye in the past, e.g. high stam regen options for dodge rolling. At the end of the day I went back to slotting Dampen and felt noticeably tankier, however I feel stamina sustain is still important. In CP, with around 12.5K stamina, I prefer some stamina sustain over a higher pool. For my playstyle I need either high stam regen (1.2K) without Dampen or just over default stam regen (800) with Dampen. I currently play the latter option and a Meridia's Blessed Armor back bar. That set is pretty fantastic to get you out of trouble without putting a Shadow Image up. If you haven't looked at it lately, examine how it's been revised. It really suits magblade. It's particularly good against small-scalers. Where it can let you down is against organised groups who put out a lot of AOE.
My offense is based around Caluurion. The main combo is Cloak -> Elemental Weapon -> Light Attack -> Soul Harvest -> Fear (Caluurion). I used Lotus Fan in the past, which plays nicely, but the damage from an Elemental Weapon combo is much better, not least because Caluurion gets buffed by Soul Harvest in that combo, whereas when you open with Lotus Fan it doesn't. It's still not particularly strong burst. You will not successfully gank decent / tanky players with this, but the build plays well in open world in general.
I'm currently wearing just stat pieces to pad out the rest of the build, but you could wear Zaan or Balorgh with this. I just wanted the extra magicka and stamina. If you don't care for Meridia's, then Bright-Throat is probably the best option. That set gives you magicka for better shields and it's 5-piece bonus counts towards idle magicka regen whereas most set bonuses don't. This gives you some flexibility. You can reach 40K+ magicka with Ghastly and use 1x stamina recovery enchant on jewelry without sacrificing your perma-cloak sustain. Another interesting option is a potion cooldown extension glyph, which actually works out at +4.6 seconds (not the 3.6 indicated by the tooltip) and brings immovability to 15s and detection to 20s from a potion, increasing your "I don't need stamina" window. On the other hand you can switch to Hissmir Fisheye Rye with Bright-Throat's without completely compromising your magicka, which gives you something like 1.3K stamina regen.
Potions are a tossup between Immovable / Detection / Magicka or Major Sorcery / Detection / Magicka. I prefer the former on the whole, so no Major Sorcery in the build. The final touch is that Infused Restore Health enchant. The idea is that between Siphoning Attacks, Swallow Soul and the enchant you can stay on attack a little longer. This works sometimes. Notably you tend to win in a straight face-off with a jabbing magplar, if the magplar isn't quite full CP or simply not built as aggressive as it should be.