Vaal lighitng build

Hi, I am trying to follow this guy build:

https://poe.ninja/challenge/builds/char/Alifek/MicsTalamoaning?i=0&search=class%3DDeadeye

but I cant understand why he has enough mana regend to spam lighting skill.

Could someone please help me?

Thank you

He´s got mana leech on his cluster jewel.
"Fuel the Fight" is the notable you are looking for.

Until then you can simply invest 1 point into the "Essence Sap" wheel for the exact same effect. This will do just fine, as long as you are dealing enough dmg.

oh nice, thanks. Im thinking putting 2 cluster with "Fuel the Fight", plus the node "Essence Sap". Hopefully enough to spam LA.