Ended at level 19. I guess the legendary armor and shield aren't needed. Didn't need more than 1 HP throughout the last fight.
Compared to my last WIP, I did slay that hydra boss over a dozen seconds faster. It was just a matter of raising my Arm Strength during the fight so that the Blade of Muramasa actually does more than 2 damage. Sword of Flames was sacrificed for inventory management purposes.