Scion Onslaught Spark Light Base converted to Cold and Chaos

Don't want to give many spoilers on this built. For the moment I just want some feedback from you guys.

This is my passive tree:



This built has permanent onslaught and 100% chance to shock and a bit of freeze( 40-50%).Problem is that I lack damage to take and kill big bosses
Must mention that I have 95% pierce chance with spark a lot of projectile speed and many more.

My current energy shield is 3 k using The Best Fur Shawl Vall Regalia

Want to know ( I have light to chaos dmg conversion) what is best ?
I give chaos, and cold dmg even if I use a spark gem. What kind of passives is best to take ? The chaos ones ? the elemental damage ones or the cold and lightning damage ones ? What about the jewel areas ? Shall I focus more on them ?

Regarding energy shield how can I increase it more ?

For items see my character SparkBang