Tentacles

The tower's walls are crumbling, covered in mold and reeking of whatever these fish creatures are while the floor is coated in their bile. There's a spiral staircase and humming audible from above, which Svenya and Carmilla go to check out. Though there don't appear to be any other creatures left in there, I don't like them going off alone and after a few moments summon Kuukivi back into the amulet on my wrist, leaving the others to guard the entrance. The source of the humming is soon apparent, a crystal ball embedded in the wall, glowing with a beam of energy coming from - or going to - a large stone tablet outside, and from there to more tablets. While we don't really know what this thing is, it seems to be connected to all the poison around, and may be summoning the creatures we just fought.
 
Outside the tower, we can see not just more of those creatures, but giant tentacles coming out of the water! They're busy fashioning more of those purple webs from all the poisonous ichor about, but I can't help but wonder where they're coming from - the river is far too shallow to hold a creature large enough to wield such limbs. Could they be growing directly out of the river bed, or perhaps are there portals allowing the tentacles of a real kraken through them? Perhaps there's a massive underground water reserve here that isn't visible from above.
 
In any case, if we can disrupt this crystal, we might be able to disrupt the poison that's been wracking the environment. Given that magical crystals currently channeling large amounts of energy have a tendency to explode when you break them, we all step as far away from it as possible, and I throw a windborne dart at it. It glances off, but shifts the orb slightly, the light that was channeling through it now much less focused.
 
At that point we hear something rising out of the water outside - we go to look out a window and see a large figure, almost elvish but distorted, dark greyish skin and tentacles all over him. He starts making some generic villain monologue, blah blah I'll poison everyone and summon the kraken and you can't stop me, before Carmilla shoots an arrow right through his head and the illusion collapses in a splash of water.
 
Ugly poison man out of the way, we keep trying to hammer the orb, Svenya hitting it with and illusory dagger with much the same effect. We notice now though, that it seems to be moving; it's possible that we don't need to break the orb, but might be able to merely move it out of place. We call Jormund up, and with all three of us together putting our weight on a spear, we manage to pry the orb out, where it pops through the wall and splashes into the water below.
 
There's still magical light shining into the room, but scattered now without it's focus - I guess we know which way it was flowing. The tentacles outside can certainly sense that something's changed; they're now waving wildly around as if trying to ward off an attacker or repair the damage, though they don't seem to be able to accomplish anything. As we walk out along the side of the tower, getting a better look at what's channeling the magic, we see several stone tablets atop of large rocks. Beams of magic connecting each one, and at the end of the chain is another tower like the one we came from.
 
Each point the magic flows through seems to channel and expand upon it - if we're going to remove this poison for good, we're probably going to have to destroy all of them. I take the lead, riding up to the edge of the river on Kuukivi before launching off of him, two massive tentacles whizzing by me as I hit the tablet with a loud crash and-
 
FUCK that hurt! I miscalculated the trajectory of my leap, sending myself into a tumble as I tried to correct it with my magic and ending up banging my thumb knuckle on the rock. Though I tried to scramble out of the way, a tentacle grabbed me, and by the time I had escaped it's grasp Jormund appeared to have the tablet under control, so I ran off up river towards another tablet.
 
As I near the base of anther large rock, a large fish man grabs my attention, slowly slithering towards me with his harpoon raised. He throws a lightning bolt at me, striking me square on the shoulder as I try to dodge, and-