[Nerwen]

Hmmn... No, I don't think Turgon will fit either. His throne may have been in Gondolin, the "Hidden Rock"– but he didn't end in a "black pit".

But that does have me thinking about First Age kings. Could "B"– the indented party– be Finrod Felagund? That would tick all the boxes, anyway. (The "spears by night" part would then refer to the Fen of Serech incident in the Dagor Bragollach.)