Bonfire locations for Trails of Treachery DLC.
All Bonfire Locations
First bonfire just after freeing the sleigh. Same path as first grim.
Bonfire Two (Right Path)
This is assuming the path you take after cog mid event takes you right towards the hill. It is just before you drop to the sleigh, just after climbing the hill.
Bonfire Three (Left Path)
This is assuming the path you take after cog mid event takes you left, towards the rope elevator. It is just before you drop to the sleigh, just after exiting the cave.
Lighting the two available bonfire unlocks a loot room just before finale. To get the achievement for all three bonfires, you have to replay the map and get the other path.