first, bonemass is vulnerable to bashing damage, VERY resistant to piercing, and i think just resistant (but maybe very) to slashing. So...use a mace.

Second, bonemass has 3 attacks.
1) he digs into his armpit and pulls a glob that he chucks off a bit. Summons 2-4 total of some combination of oozes and skeletons.
2) he grabs his stomach and rears back and vomits onto the ground. Makes a big poison cloud that continually refreshes poison duration. If you're over-geared (like high level iron armor, good shield, high end foods that have lots of regen) and have a poison resistance mead, you can just sit in it and smack him through it....otherwise run when he rears back and kite him out of the cloud.
3) he pulls back one arm or the other and does a smack. No poison damage.

Third, to prep the area, you should probably make a portal, a workbench, and use the hoe to flatten/raise the ground so that there is a large area out of the water...you don't want leeches chiming in on your fight, or to be slowed.


- when he does attack #1, run to the glob's landing spot and kill the enemies while bonemass is moving to you. You don't want to have the adds punching you around while you're trying to position for bonemass.
- when he does #2, run back, well out of the cloud and make him follow you. Use this time to regen stamina or pop him with fire arrows (they don't do much, but its progress)
- when he does #3, either dodge backwards or block, then you can unload 2 consecutive 3 hit combos before you need to block/move again.

- Always use bludgeoning damage.
- Always deal with the adds fast - especially skeleton archers. (if he tosses a glob on top of the altar he's summoned from, the skeletons will be stuck, but the oozes can get down).
- don't be afraid to back off and wait for some health regen if you missed some dodges or blocks or the poison got too bad....the adds make him a very annoying boss to corpse run to.
- fight him at dawn...its a long fight
- make sure you have enough poison resistance mead...its a long fight.