Originally posted by Raviel:

Bonemass is probably the best boss in the game currently.

It isn't too easy to cheese and can be a treat.
4rth boss is so bugged it's easier than the first, and first is easy as hell...

Haven't fought the 5th, but sounds like its bugged too, so, yeah :/

Bonemass is the only boss that fights back, and not just waits to die.. even so he is completely helpless in coop.

It's freaking sad when a 0 star goblin is more challenging than a dragon boss...
Not even talking about 2 stars...

The 5th boss was actually decent as well. You'll need to get in close and melee him and he hits very hard so you have to be careful as you have a real chance of dying, especially if furlings and deathsquito's sneak in behind you while you're melee attacking him (yeah I died once that way).

You really need fire resistant potions and bonemass and healing meads and the top foods. But the key really is fire resistant meads.

Just avoid cheese strats as that takes away the challenge and feeling of accomplishment IMHO. And finding 5 totems to unlock it may take a lot of exploring. Either way good luck.