I kinda made this build on my own, it kills 5/7 ubers (exarch too hard, awakener haven't tried).

https://pobb.in/yZGAKruUbTia

I have ralakesh's impatience in my inventory and double tap it to get max charges instantly in pinnacle boss fights, since the ramp is pretty painful otherwise. Once you get to max you sustain with pcoc though.

I proc EE with an abyss jewel that adds a miniscule amount of lightning damage which triggers from impending doom/doom blast (source of cull as well)

I mainly posted because i feel like i hit a wall on scaling it further, so im open to suggestions.

Also sharing it for people who might wanna try something like it. You curse enemies with frostbite and ele weakness, hexblast, reapply frostbite, hexblast, reapply ele weakness. The doom mechanic allows you to move around and dodge stuff without really missing out on dps.

Here's me max shocking uber maven (and losing currency farming her in the process) https://cdn.discordapp.com/attachments/449906208615432194/1021329922700095538/unknown.png

The build is kinda based on Devon's build which i played during the second endless delve event https://www.pathofexile.com/forum/view-thread/2936815/page/1 . My version is different enough though.