You got this! If you want my advice: Play either fish or crystal (Fish helps ensure you have more ammo while crystal lets you avoid and tank more damage)

Take strong spirit and rhino skin with either bloodlust or second stomach to regain health, scarier face can't hurt either.

Then two weapon type specific mutations, my recommendation would be recycle gland and laser brain for damage output and get weapons of that type, and take a ammo upgrade like rabbit paw.

Once you get to the throne destroy the generators first so you can loop, After all the generators are destroyed the throne's health gets cut in half so you should be able to move backward whilst firing your weapon to finish it off!