Thus far, the greatest individual villain that the party has directly engaged with would be the Song of Thorns. Which is ironic, because it is by far the
least person-like of the villains they've dealt with.
See, there are four main threats (since the Song was definitively
ended): the Zil al-Ghurab (Raven-Shadow) assassin cult, led by the Grandmother of Shadows; the Shadow Druids, whom the party has learned form a horrifying hive-mind spirit controlled by Dawud al-Jana, whom they have never met; the Cult of the Burning Eye, which the party knows is led by some powerful and ancient force (the titular "Burning Eye") but they don't know
what that force is yet, having only dealt with its lieutenants; and, last but not least, a black dragon that has concealed itself in their city for years and years, slowly shaping it to be its "hoard," whom they have yet to see directly. Each of these is either led by an actual person, or led by something that is person-like.
The Song of Thorns...wasn't like that. It was a spirit. Spirits can be a lot of different things in this setting, but they tend to take one of four forms:
- Elementals and other manifestations of raw physical forces
- Things in the physical world (both natural and artificial) that have existed for a very long time and thus taken on significance
- Abstracted ideas, entities, or concepts which have mattered or which people have cared a lot about (this includes stuff like the spirit of Owl or The First Oak)
- The "whatness" (formally, quiddity) of living creatures, usually beasts but sometimes other stuff too
Druids generally tap into the first and fourth things, drawing those spirits into themselves or instantaneously evoking their power, while shaman primarily tap into the second and third, binding or compelling their service.
The Song of Thorns probably started out as a spirit of the second kind (a natural spirit tied to something), but was corrupted and expanded into an infectious mind-virus, turning it into the third kind of spirit. Fundamentally, it was a spirit of savagery and entropy: decay, not in the rot sense, but in the collapse and breakdown of systems sense. It would steal the abilities of beings it infected, but the infected would slowly become more savage and brutish, losing their intelligence and even sapience until finally succumbing, meaning the Song of Thorns would grow
stronger but couldn't truly hold onto any amount of sapient thought for long. This made it too basal to be a
person in the proper sense; it was driven solely by instinct, like an evil, thorned kudzu with the intelligence of a predator. It wasn't in any way cruel or evil, but it was an incredibly dangerous threat to basically all animal life, so the party
had to take it down.
And they did! It was a super climactic battle after they'd collected together resources and allies in the strange pocket dimension where the Song was trapped. Through their efforts, they elevated a counter spirit (they found a "predator," as one druid advised them to) to a similarly powerful state, employed various tools to weaken the spirit, and then finally transitioned into the Spirit World where they could destroy the Song of Thorns at its metaphysical root, rather than just damaging the massive plant body that was its "totem." The Bard even leveraged the fact that the Song was, in fact, a
Song, re-writing its lyrics to bring it to an end, rather than exalt it for its victory over the beings it had destroyed in the pocket dimension.
I think this villain worked, overall, because it was the right mix of "personally scary" (hitting ideas and feelings that meant a lot to the players) but "impersonally active" (not really being a "person" in the proper sense.) Further, I made sure to let the players know that they were taking a great risk: by facing the spirit in its own lair, they were risking their protections against it failing, and if they got absorbed into the Song, that would have been...very bad. The Battlemaster would have given it a brilliant sapient mind that would never break down (due to a magic item he carries), the Druid would have given it the power to make
any person it infected able to shapeshift, and the Bard was the most dangerous risk of all, because his magic IS song--if he had been infected, the Song could learn how to
modify itself, which would make it nearly unstoppable.
Thankfully, none of that happened and they actually kicked major butt, securing a full and unequivocal victory, though at some cost to the group. (Druid's player was going on hiatus anyway, so the timing was really good IRL, but it was definitely a somber moment so soon after a thrilling victory.)