3.14 Toxic Rain - Leaguestart guide with in depth crafting and gearing section - updated

First time playing TR and I am loving the build. I only have ONE issue which is mana sustain during bossing. I have to kite around while my mana regens to shoot more TR. is this normal? My TR cost 13 mana so I'm not sure where else to fix this.

https://pastebin.com/9SBy5CBV

Also open to any inputs for improvement. :)