A tale of two Krakens
by Marc SaindonDoing my bit for Kraken week, so my idea is that there are two Krakens in Mystara (currently): one is in the Northern Reaches, known mostly by its Ostlander name of Kraken, while the second, lesser known critter, is Rogo-Tumu-Here (according to his Makai name), who haunts the Sea of Dread. Each is of the opposite gender (pick which is which as convenient for your game) and have not encountered the other. Yet.
Rogo-Tumu-Here might also be the same monster that harassed the Milenians during their migration to Traladara.
The campaign idea might work as two campaigns, one centered around Ierendi, the other in the Northern Reaches. In between games and modules (e.g. playing the Isle of Dread for the Ierendi group), players get reports or see for themselves destruction left behind by some unknown forces. Reports of the monsters are hazy at first. The destruction should follow a path, with coastal villages being destroyed and fleets being attacked in a clear pattern (Ierendi players will see incidents going north-east, Ostland players will see incidents going south-west).
Eventually, this will end in a Roman galley re-interpretation of Jaws, in which the players and the Thyatian navy figure out that these one-of-a-kind-monsters are an actual species and can breed to greater numbers...
Notes:
Rogo-Tumu-Here
(Image from: https://www.deviantart.com/cellohanada/art/Polinesian-Maori-Octopus-610273947)