Need some help.

The best stage that my knull can clear fast and easy is stage 4. I'm trying to push him on higher stages so I tried playing him at stage 6 and 7. The damage is there but I'm wasting so much time during phase 2 (30-22 bars) and 3 (21-12 bars). My procs are all over the place and the rots are a mess.

I'm even considering giving him a Rage. I need some tips and advice on how to play him on the latter phase of the wbl fight.

Here's the screenshot of my run: Knull WBL run

Here's the build that I have: Knull Build

Raid level is at 270. 39% AA and 14% PA 2% pierce on cards.