For Blade Dancer: Lineage of Light , the easiest confirmed source I found for Monster Bone is the crafting guide footage showing it as a required material for the Demon Slayer weapon, but it does not by itself prove a drop location.

The clearest location clue I found is that Monster Bone / Mystical Bone -type materials can be dropped by enemies in Nehprem Mountain , and by a War Dragon that appears when monsters fuse together in that area.

What to do

  • Go to Nehprem Mountain after progressing far enough for that area to unlock.
  • Fight enemies there, especially fused encounters involving the War Dragon.
  • If you need it for crafting, check the weapon shop/crafting path tied to the quest or recipe you’re following.

Note

There’s also a forum thread about beast bones in Blade Dancer: Lineage of Light mentioning morphed wolves, but that thread is about a different item, so I wouldn’t treat it as direct proof for Monster Bone.

If you want, I can also help narrow this to the exact monster and area for the specific version of the game you’re playing.