always prepare before fighting the elder, i feel like it needs to be something that is explained better in the game but every time you defeat a boss you are opening up new possibilities in terms of both pros and cons.

you get better materials yeah, but you also unlock harder raid enemies.

so with this known, it is always best to learn what is actually going to happen after you defeat a certain boss.

without spoiling anything, the basic principal is that the harder enemies from the current biome you are in will spawn in raids AFTER you beat their respective biomes boss.

you learned this with trolls, the rest of the game works the same way.

so be prepared when you finally feel like fighting bonemass because he is pretty much the point of no return boss.