His Scattering Calamity Stormweaver: Where to go from here?

I think you’ll find that the best case scenario to use this skill with is probably a zero duration Titan build. It makes things like ember fusillade and Scattering Calamity instant cast their projectiles. People usually pair this with either a life stacking and time of need style or mind over matter and stack mana as their life pool and use their 1500-1800 life pool to cast the spells. They’ll usually utilize all Time of Need in order to regenerate health and become effectively immune to curses/ailments as well.

Here's what I was running as a Blood Mage:
https://pobb.in/W0SwjOPsN5__
Still plenty of room for improvement, but maybe it inspires you.

I would say a good general increase to your survivability might be to get a 2-3 socket covenant without the “life cost equal to 100% of mana cost” and instead run lifetap or similar. This alone would boost your ehp just because you won’t be getting hit as hard on the mana regeneration downsides to MoM and EB. As long as you’re retaining your spell leech it should self sustain your hp too.

Finish your ascendency and get the other two Arcane Surge nodes. The StormWeaver is good at applying ailments. It might not be a bad call to make your skills also contribute to chill. That should make mobs slower or frozen to give you more leeway.

Ofc you could use a headhunter if you wanted, but if you prefer not to you could probably do with swapping to some kind of different belt. Even if it isn’t unique I think you might benefit from something other than midnight braid. It’s not a bad option though.

2 dead stats on gloves and ur ring too really, accuracy in helmet is pretty much no use,+3 spells on amulet, add esh’s radiance and rakiatas flow on calamity instead of cold penetration and siones temper