Need help for build upgrading

I'm looking to upgrade this build I've cooked up on my own
As of right now, it can deal with most T15 maps with acceptable juice
The current issue is the DPS. It is very long agaisn't end-bosses

I have over 400c and 1 divine to upgrade and I want to try and push it a bit more beofre moving onto a new build.

I think I made a wrong choice by going Cold instead of lightning, but it is working and switching damage Type might pricier than upgrading.

Build


NOTE: If you have some specific items, please share a trade link to help.
I prefer possible items, not theorycrafted items that cost 30 Divines.

So I managed to get this fairly cheap (Under 1 Div)



Currently reaching 500K dps. Which feels low for the amount of defences
https://pobb.in/Np0Y7fbufzJe


It is clearing content, but I'm wondering if it can reach better numbers with some real items or cluster. I don't mind respecing, as long as Cold tornado is kept