which support gem for conductivity or any other great curses for bosses

[['w']]

playing as lightning monk, have a very hard time to kill the 4th boss in sekhema, mostly because I run out of mana, already got lightning pen 60% on one skill, wondering if it is even useful to go for 90% lightning pen with conductivity and how to support it for more single target damage.

Even reached the boss with 13k honour and 100% honour resist, still only got him to 1/5 of health because I can only attack 10 times in 30sec because of mana issues.