Cocytus is the being Aleister the Invoker summoned into a back alley of Pentamarone in Session 11 — a vast, draconic elemental of ice and running water, with blue light moving through its body like blood.
Nobody present had ever seen anything like it, including the adventurers who had come to Pentamarone hunting Aleister specifically because of what he summoned in their dungeon. Whatever he called up in those ruins, it wasn’t this.
What the Party Learned Fighting It
- Cold damage slows it. The single most important discovery of the fight, and it came from the enemy: the bandit mage’s Ray of Frost landed and part of the creature’s body froze solid, halving its movement. Every frost effect on the board after that was a tempo win — which is why Leif’s Ice Knife carried the encounter.
- Slam attacks, two per turn. One landed on Drolta for 28 and put her down — the first death saves of the campaign.
- It engulfs. It swallowed Red in brown-bear form: 20+ damage, knocked out of Wild Shape, then restrained and suffocating inside its body until he escaped on a Strength check.
- Large pool of hit points, ground down slowly by the party and the adventurers together.
- It is not loyal. Consistent with the adventurers’ account of the last one, it stayed and fought after Aleister flew away and abandoned it.
How It Died
The swashbuckler of the adventuring party (named in Session 12 as The Sundered Watch) finished it: she ran up the back of Red’s lion form, launched off it, and drove her rapier through the beast’s eye.
Aftermath (Session 12, September 23, 2026)
Nobody searched the corpse. When the party described Aleister the Invoker to Madame Verre at the WitchCrafters guild hall, with details down to the staff he drew from the creature’s chest, she asked:
“Yes. I very much do need to check out this monster. Is it still there? You left the corpse untouched?”
Then she teleported away to examine it, reappearing only long enough to toss Leif his staff. What she found has not been disclosed.
Genni had perked up at the word “monster” when Aren described it as a water creature, something like an elemental but “scarier looking,” that could be slowed by freezing parts of it, and went straight to tell Verre.
Why It Matters
Cocytus is the party’s first direct look at what Aleister the Invoker actually does. It is not native to Astrodia by any account available — which places it in the same uncomfortable category as The Orb’s prisoner and whatever speaks to Leif as The Whispering One: things from outside, that people in this world can nonetheless reach. (Session 12 context: Verre’s account, via Leif, is that the Great Cataclysm opened a portal to another world and that beings came through it; whether Cocytus has any connection to that is not established.)
Related
- Aleister the Invoker — who summoned it, and then left it
- The Sundered Watch — whose swashbuckler killed it
- Madame Verre — went to examine the corpse
- Pentamarone — where it was summoned and killed
- Leif Kalanchoe · Drolta Amara Tzuentes · Harlan “Red” Reed · Úlfr Kveld — the party that fought it
- Sorath (The Whispering One) · The Orb — the campaign’s other outside-the-world entities
First Appeared
Session 11 (September 9, 2026), summoned onto a rooftop in Pentamarone. Killed the same afternoon. Its corpse drew Madame Verre out in Session 12 (September 23, 2026).