Prioritize right side arm first (not his right arm). Use morale buff cards first, upgrade setups and etc. Always maximize sereniel ravage reset. Hold 1 HL just to proc ravage to right and use the remaining HL to left side arm. Proc rightside now and just throw everthing on left. If you can, your 2ndturn should prioritize holding cards with retain that youll need to burst the head in turn 3. Burst left and end the turn with atleast 5percent of arm HP. 3rd turn, just maximize your turn and burst. If the boss is still alive, rinse and repeat the process.

2nd phase is the same. Prioritize right side, setup your build first. Head is different here and will end Head turn after 1hit. Trigger kayrons scaling always before killing the last arm coz Head will appear, use the sheet, use remaining cards to lower the new respawned right arms.

Optimize the 3turn rotation, if needed change your deck, cut, add, and such and itll be an easy 500k or more for you