Tips for hard mode executioner

[BardzBeast]

I'm working on the first hardmode boss.

Playing Freyna. Level 100 reactor which has been improved twice. using guns with toxic bonus and got electric resist modules upgraded etc. Staying alive isnt an issue.

I have cooldown reduction on my Z tox gun skill but it still takes aaaages to cooldown.

He has about 40-50% of his HP bar left trying solo.

I am not using Tamer as to me it seems overtuned and would make the fight easier in the wrong way. What else do I need to do?

At this point I think all I can do is make more catalysts and a energy activator so I can stack more mods on my Freyna for skill damage. Any other tips? I can never destroy the little tube on his back while in Frenzy, at this point I just wait for it to end and save the ammo.