There was another thread on awakening this set recently, but as my suggestion goes in a completely different direction, I decided to make my own topic.
Present Situation
The Aetherstorm, or Arcane Tempest, set is an epic accessory set (2x rings + Amulet) which provides bonuses to Wind Devils and Devastation while granting a unique Aether Lightning ability. Now, Aether Lightning is a beautiful spell and it would be nice to have a level 94 variant, but I think it would be a waste to simply upgrade it and add another skill level or two. Therefore I want to take a moment a consider both the existing situation of the set, as well as Druid itself, and propose a unique set identity.
As-is, the Aetherstorm set is a Druid caster set, and Druid casters presently have 2 different archetypes through the Trozan set (TSS + Wind Devil) and the Ludrigan set (Panetti + Storm Totem). Now, if we were to simply upgrade the existing set we would run into the problem of it both (1) being extremely similar to the existing Trozen set as both sets are what we might call falling rock Druids with support from Wind Devils, and (2) be entirely equip-able alongside the Trozen set without any trade-offs required. Generally speaking new legendary sets attempt to enable different playstyles from each other, and they usually require the player to make hard decisions so as prevent access to the two powerful full-set bonuses simultaneously. The big difference between the Trozan and Aetherstorm sets is the Aether Lightning ability and I think we should use this as the basis for developing a 3rd Druid caster archetype.
Design Direction - Lightning Caller
I think the third Druid caster archetype should be a full (aether) lightning caster. Since we will have Aether Lightning to function as our standard attack ability (i.e. no cooldown attack), the next question is what cooldown based abilities should we combo with it. In this case we run into another problem, namely that Druid’s native caster potential has already been exhausted by the Ludrigan and Trozan sets. This potential is so quickly exhausted because Shaman locks several abilities behind using a 2H weapon, while Arcanist does the same thing but by requiring an off-hand. Yet, with the addition of new skill modifiers that can bypass ability weapon restrictions, we can now begin conceiving of set combinations which were previously impossible, and that is what we ought to do here.
Druid already has a chain lightning spell and it is called Primal Strike. The issue is that Primal Strike requires a 2H weapon. At the same time, Aetherstorm gives bonuses to Devastation, which requires a caster off-hand. We need a way to bridge the gap here and the answer is to add a 4th set piece to Aetherstorm which is a 2H ranged weapon with a skill modifier that allows it to cast Devastation. This weapon is not meant to be used to attack except to proc Primal Strike, so it should have high casting speed but no additional attack speed; in general it ought to have caster stats. It should also be split between Aether and Lightning damage (or have polarized versions, one with full conversion to Lightning, the other with full conversion to Aether) and convert the leftover damage from Primal Strike (Physical) and Devastation (Fire) to one of these two primary damage types.
Most sets also enable a 3rd class and I think there is an obvious addition to our lightning theme and that is Occultist with Doom Bolt. Doom Bolt already has a MI converting it to full lightning, but this is a 1h weapon and so is incompatible with Primal Strike. By letting the Aetherstorm set convert Doom Bolt to Aether/Lightning damage (or just Lighting with a Lightning polarized weapon, or Aether/Chaos for an Aether polarized one, which would synergize with Fabric of Reality), it means that both Conjurer and Warlock would gain new (aether) lightning caster archetypes as well.
Summary - Final Proposal
In sum, Aetherstorm should receive a 4th set piece, a 2H weapon, that enables Druids to use Primal Strike with Devastion and Conjurers to use Primal Strike with a fully converted Doom Bolt. All 3 combinations would use the set-provided skill of Aether Lightning as their standard attack while waiting for these heavy hitter skills to get off cooldown (I’d also remove Wind Devil skill bonuses and replace them with Primal Strike and Doom Bolt bonuses and modifiers). The addition of a 4th set item would ensure that the Aetherstorm set is no longer fully compatible with either Trozan’s or Ludrigan’s, meaning players would need to make a choice between which set finisher bonus they want, similar to how Nightforged Set works with Runebinder. As per the numbers, I’ll leave that to the experts, as I am only here interested in the conceptual design.