You when playing this build (only 4 fingers needed).
Grim Tools for the impatient:
Idea:
Since Storm Box of Elgoloth and the Allagast set got heavily buffed this patch, I decided to try it out and see how the build is performing.
Concept / Build idea:
This build revolves around the Allagast 4-piece set, giving strong bonuses to Trozan Sky Shard (TSS) and Storm Box. It uses the item / devotion synergy of aether and lightning damage, resulting in a dual damage type build with a split of approximately 60/40 - Aether/Lightning. While Storm Box is your AoE / trash killing option, TSS aims at nuking down harder enemies, with more projectiles (that will shotgun) and high crit damage.
Ingame Stats:
Gear breakdown:
(not everything)
Pants: There are many good options here, pick your best one.
Rings: The Allagast rings give very nice skill bony + have the exact stats you need, pull 1 out by preference.
Off-Hand: This item allows you to shotgun consistently. Prefix: Thunderstruck / Glacial / Sandstorm, Suffix: Celestial Wrath for +2 Storm box. You can also use Scion of Celestial Portents but i don’t like the TSS spread + this requires you to get +2 to Storm box somewhere else.
Helmet: Bonemonger lets you spam Inquisitor seals, letting you reposition easily and gives additional Aether RR.
Relic: Eternity is good but not amazing, on HC go Serenity.
Key Devotions:
Viper: RR, gets proced by spear of heavens, so only 60 % effectiveness.
Widow: RR.
Scales of Ulcama: RR + you have up to 96 % Vit → Aether meaning this is also good for sustain.
Dryad & 3p Behemoth: Sustain.
Spear of Heavens: Crit damage / OA / Lightning and Aether Damage / Procs Viper.
Rest aims at getting tankiness and as much spirit as possible.
Playstyle
Word of Pain (WoP) and Storm box apply RR, so cast these first, then TSS. close range enemies take more damage due to Aura of Censures (AoC) RR and enemies inside your seal even more. This Build is by no means a quasi-meele character but if the enemy is not dangerous go into melee range for the sweet AoC RR and DR.
This build also needs Tons of OA, due to TSS having innate + 70 % crit damage. This means that your crits slap really hard. Storm box helps with bringing the enemies DA down while the deadly aim proc gives you more % damage and OA / crit damage leading to high TSS crits.
Feel free to use mirror offensively (going melee) because not only do you have acceptable CDR but Eternity brings down the CD even faster. (ON SC OF COURSE)
Performance
Ravager of souls
Callagadra
Crate of Entertainment
SR 75 - 76
Obviously, Lokarr / Mogdrogen are easily doable and higher SR shards are also viable, but your damage drops of sharply after SR 80.
Alternatives
You can go a more lightning damage route with the 3-piece Cataclysm set, but i did not try that one out jet and on paper it doesn’t look as good in my opinion.
Closing Statement
I think a true dual damage type build that works is very cool, and it actually feels good to play. This build is very safe, and I still don’t have a single death on the character (yet), making me a quasi-HC player, right? 
Have fun with the build, and thanks for reading!