It’s a matter of not feeding the monster, if you have less clothes, the monster can’t feed on them.

you need to use DoTs, like fire damage for example, this’ll negate the regeneration.

ontop of dps, debuff the boss’ resources so it has a lower health pool (reduce your clothes and clothes only worn once on non-humid days/less active days can be reused)

You guys need to up the DPS. You can also easily cheese this boss: set the pile of laundry on fire.