6074: Black Falcon's Fortress
This set, released in 1986, is another mid-sized castle which can open up. One interesting aspect to this castle (which I only know about because I own the 2002 re-release) is that the outer walls of the castle have holes for pegs, meaning that you can connect other sets to it in order to create larger castles. Otherwise, this set is a fairly standard design. The front entire front of the castle is raised up which is something different, but not something significant. One oddity, however, is the lack of any swords.
6085: Black Monarch's Castle
Released in 1988 (the year of my birth!) 6085: Black Monarch's Castle is a dark monolith among other Lego castles. It's an enormous set, with two towers in the back and a two-story gate tower in the front. This set also uses a flat baseplate (the last major castle to do so) and has hinges so that it can open up for play. The attached army is the first iteration of the Dragon Knights, another faction among many. There's not much else to note, except again the lack of swords, which I do not understand.
6059: Knight's Stronghold
A simple expansion to 6085: Black Monarch's Castle, this set is the epitome of the "Battle in a Box," with both Black Falcons and Dragon Knights. Fairly basic design, but the ability to add it to an already existing set and the inclusion of two warring factions makes this an interesting set. Additionally, it calls me to question which of these factions are to considered good and evil. More than likely it is futile and immature to label these factions as being good or evil, when really they may just exist as opposing factions fighting for land and glory. It may not be until 2000 with Knight's Kingdom I that we can with certainty assume that one faction is good and the other evil.
Part three of this four part series will be on Castle sets in the 1990s.