Halls of the Blood King
This hardbacked scenario for Old-School Essentials presents the manor of a plane-hopping vampire who claims dominion over vampires and imposes a blood tithe on them. One of his “subjects” has failed to provide his tithe and the Blood King has arrived in the character's world to impose his will over his errant vassal.
The scenario is presented as an old-school mid-level run on a hostile stronghold but it feels like it would work better in a more planar-based game where the various intrigues and sub-plots can play out. Alternatively you can drop the conceit that the Blood King is here for a specific time (the Blood Moon) and have him arrive as a new faction into an existing situation, present until he chastises his wayward child and obtains what the feels he is owed.
Some of the NPCs presented are intriguing: the vampire refusing to pay the blood tithe has been cursed with moral feeling and therefore doesn't want to murder people. He's hiding in the castle plotting with the king's adopted daughter while an enchanted vampire look-a-like is tortured in his place.
A vampire hunter has become trapped within the manor and is unable to escape but is a wildcard threat to the occupants and a potential ally for the invaders. She has captured a vampire and is subsisting by drinking their captive's blood.
These are vivid portraits of desperate people but sadly more interesting than the Blood King himself.
The castle also has a hive mind fungus infection which is one idea too far for me, although the idea of using an infestation to your advantage would have appealed to several of the groups I've played with.
There is also a cosmic astronomy theme with minature worlds and a heart hidden inside a star. I found it interesting but I'm not quite sure it really fitted in with the rest of the blood, flesh and horror motifs.
I like the rich, electric illustrations by Justine Jones but in a couple of cases (like the Shadow Hounds) the art and the text don't agree. I think you can pick which you like but the art is definitely the richer and more evocative if a little bit more conventional.
The biggest issue I have with the scenario is that it is half-sandbox and half-frozen tableau waiting for the players to arrive and allow the plot to progress. The rebellion against the king isn't a ticking bomb but also doesn't feel like a slow-burning situation where the characters can make a decisive difference. Only the situation with the vampire hunter makes sense as a status quo that the appearance of the characters can majorly alter.
Overall I think this is a book to take ideas from but its more inspiration than play ready.