This is my Unleash Hexblast build that I've been working on for Sanctum. It has finally reached 100m burst DPS on bosses and just melts everything it faces. The build has ~150ish div put in possibly a bit more with prices as they are now.

You can get started with much less currency quite easily the main things you need are the helm, 6L shavs, 2x Void Batteries and a curse on hit Vixens (enfeeble or temp chains will work). Your main way of sustain is via mana regen which is helped by the higher levels of Clarity, if you are going for lower investment then you need lower levels of Clarity and normal arrogance support which shouldn't be as bad because you'll also have a lower cost Hexblast.

POB: https://pastebin.com/knUJdEJJ

EDIT: Sanctum: https://youtu.be/MzL1qr_mABQ Very easy with the damage and freezes.
Maven: https://youtu.be/1_UA6l7KlyI Made a couple mistakes but the damage carries me quite easily.
Map + Elderslayer: https://youtu.be/_yQh0jgut1I
Elderslayers Invitation: https://youtu.be/Dsy3Mnbj2bc
Oshabi: https://youtu.be/zXlSC4f7vZ4
Drox 1 shot: https://youtu.be/Za0Hdd3Z6eM