I think this game makes you think. the bone mass is very hard and I failed.
however I started the game again and now close to facing the bone mass again but this time, following advice from you tubers, especially um fire spark or something, he and another showed a way to get him and that is making a house in the trees way up in the air out of reach of him and all other enemies on the ground and not worrying you, . then with a hole in the floor and frost arrows, good bow experience level, and a good bow you just shoot him from your tree house.
cant say it is easy yet as i am not quite there. also if you can build your house over a fire spout so he gets burned by this also.
one u tuber um damn cant remember, eso or something, went with the iron hammer really at max improvement . every thing compounds, your experience level with the bow the hammer etc the comfort when you sleep the weapon you use bla bla so as hard as it is, with the stamina potion the poison potion the healing potion and the hammer and walking not running, good food meat tails soup turnip soup, fish , clearing out all the local enemies before hand , it seems you can do it and when you succeed boy does it feel good so just better prepare yourself. it is disrespectful of me forgetting who did it in the utube video but he learned the actions of the bone mass, the melly the spewing of the poison and the throwing of the enemy spawns. and he used the hammer to kill the ball of enemys thrown by bone mass,when it landed waited for the melly punch then walked in and hammered him and he made it look easy if you had your wits about you. many many folk have killed it so if you cant, it is just you arent good enough, or prepared enough, and i may be one of those, but the house with the hole in the floor looks the way for me the melly was to hard for me, i failed but i wasnt prepared enough i think hence starting again.