I'm a sucker for perma flasks and wanted to try hexblast mines (seems like it will be good for sanctum and league mechanic which is what I want to do) so I made a POB for it and it kinda looks good. - feel free to steal and modify if interested or provide feedback on why it isn't very good.

Not a league starter but something to transition to day 4-5 pretty from poison exsanguinate/PC - You could make the swap at 85 if you really wanted to and had the reservation and flask cluster jewels, 91+ and it would start to feel a lot better.

6-7 mil DPS on a first week budget (I estimate 20 div or so on day 5?) No awakened/alt quality gems required, only hexblast is level 21, so I think it is a reasonable estimate of what you could get early league.

Defences are pretty basic PF ele conversion and evasion with ailment immunity - later game I would plan on getting iron reflexes from sanctum and run bloodnotch tech to feel really tanky. Build fits in progenesis really well if you want to take it that far.

Build does use 3X flask duration tattoos, they are only really necessary to have permanent uptime on amethyst flask when bossing/sanctum before you have a well rolled progenesis.

If gear looks weird it's a mix of gear from other POBs, some of my characters, and things I found reasonably cheap on trade. Only expensive item is +3 bow but you could run 2x +1 chaos 1H weapons and sub out empower to lose ~15% dps but dramatically drop the cost. Cluster Jewels might run a few div as well, but I think you could get started in the 4.5 mil DPS range for 7-10 div and still have decent defences.

Let me know your thoughts!