If you aren't past it yet, at some point you will need eels and fish following the mermaid storyline. That's where I am (my castle is level 8) and it is slow going. I now have the tokens to craft the loch, but not the rest of the ingredients. It will take me a while, but I will try to post it's drops, probably on the mermaid story thread as I won't remember which thread this is. Later down the line we will also need cursed items which I think come from another of the MRC creatures, also needing materials the loch drops.