I'm going to chime in, even though what I'm going to say comes with caveats. I play my warden rarely. I don't have / have not found a good burst rotation, I only do pressure. I keep returning to magicka stacking, like a sorc, because it's the only thing that's worked reasonably well for me. That is where my exploration has ended. I don't generally play vampires for role-playing reasons. For solo / 1vX I will probably always feel a sorc is better or that you need Mist Form on classes which lack mobility, but I don't have that on my warden. I think Bird of Prey is pathetic on the mobility front and am, therefore, using Race Against Time instead. I am not happy without root / snare removal. I'm also double-barring Inner Light and have kept my build simple on purpose. Took it out, briefly, last patch and it seemed quite good defensively and offensively good enough to kill bad players and pressure good ones. I play in CP Cyro / IC.

With all that out of the way, when I next take out my warden, I will try Hrothgar's plus mag stacking. The Hrothgar proc does not require spell damage to be viable, hence we can mag stack, and should be triggered by Arctic Blast. It also benefits from warden's ice damage passive. It's all a bit random, but if you can line up the proc with Deep Fissure, we may be on to something. That would probably require Frost Clench or Dawnbreaker of Smiting though. For now the theory-crafted build simply looks as follows. I agree warden sucks up magicka, but if you can sustain, you could go for a higher-mag food. Note I always use and always will use the Bull Netch for stamina sustain in PvP as it works even when you block or sprint. This is the "no Mist Form" option, I suppose. 50K magicka on the back bar for the shield. More while Northern Storm is active. Ice Comet is only really there, on the back bar, for the magicka boost.

https://en.uesp.net/wiki/Special:EsoBuildData?id=378627

Well, I can confirm that my build is working to my personal satisfaction at least. The survivability against multiple players in CP IC is decent, though bear in mind it's the event and hence these are probably of mixed ability. There are, however, a lot of them and I did fight around the flags where the PvPers tend to hang out. The build has absolutely no burst coordination, but Northern Storm, Arctic Blast and Hrothgar just lash out.

When you get focused, keep alternating Dampen with Trellis, block casting when at low health. I am all offense in the blue CP and yet this works quite well. Whoever says magden doesn't have healing, well, I don't see it. The only thing is, I'm at 2.5K mag regen and I find the class, or at least this build, extremely magicka hungry. Recovering from a low health condition can be extremely slow, if you're being pressured. 2.5K recovery is merely adequate. Bear in mind I'm using the Bull Netch, but I have no regrets on that score. You need the stam sustain too. The build is not fast. I don't think mag-stacking non-streaking builds ever are. Nonetheless I don't understand the hullabaloo about Dark Convergence. Yes, it can kill you, but mostly I just roll out of it.