Once Chompers regenerate back to full HP, you want to focus back on Chompers and push it to the regenerative state again. This will allow you to shave off a huge chunk of Conraad’s HP while Chompers regenerates back to full HP. When this happens, Conraad will gain a buff that make him gain more damage but he will also take more damage. What you want to do is ignore Conraad and burn Chompers down to 30% first so it enters a regenerative state where it will heal up.
This is a fight where you don’t want to simply kill off one quickly as doing so will cause the remaining one to enrage and gain massive damage buff.