The campaign itself is meant to be very sandbox, after the introductory scenario. The players will be residents of the small frontier village of Spiralstone, which is attacked by the vile spirits of the forest, and one of their dear friends (who is also the village elder's daughter) is kidnapped. They soon learn that the Sea Hags are behind the kidnapping, and that Imalga has returned. From there, they are free to explore the Northern Reach in search of ways to defeat her, and learn more about her weaknesses. This is a summary and explanation of all the plot elements, and some of the likely locations the PC's will visit.
The Campaign:
Imalga was truly defeated and killed by the Crimson Coil, but not all traces of her Black Tide were destroyed. What very few were aware of is that the algae of the Tide was not just another of her vile creations, it was her own body, transmuted into a swarm of plant life. At the height of her power, she could appear anywhere that the algae was present, and work her magick across vast distances. What no one except Imalga knew was that she eventually lost control of the Black Tide. She had become too massive, too powerful, and in the years following her war with Kanaloa, her consciousness slowly faded and dispersed as the algae spread across the ocean. She nearly lost her mind as her body wandered away. With a tremendous force of will, she reformed herself in her lair, but she had lost much of her power and control. For the next few centuries, she would have occasional bouts of insanity or fugue as the Tide took control of her.
The Crimson Coil recognized the power of the Tide, and they took steps to defend themselves from it. They used divine magick to kill any traces they found (Khozed Thross summoned a powerful angelic being), and after Imalga's death they managed to wipe out all of the algae. The secret to actually killing Imalga, as the Coil learned, was to pull her heart from her body before it could disperse to the rest of the algae bloom. They froze her body, cut out the heart with a sacred Sahuagin weapon, then proceeded to destroy the rest of the Black Tide. There were actually two major traces of the algae left. One was stored in a giant sponge in the wild reefs beyond the Elderstar Islands. The mass of algae in the wild reef was kept safe by the Fey spirits who were loyal to Imalga. The witch's mind and spirit were destroyed, so the algae could not revive her, although it would frequently spawn strange, deformed monsters that could manifest many of her powers.
The second trace of Imalga was left intentionally as a contingency plan, she passed on a part of herself, in the form of a worm-like parasite, to each of her female offspring. Imalga's brood was almost entirely wiped out by the Crimson Coil after her death, and by various witch hunts. Only one child survived, a beautiful Merfolk girl, her father one of the Mers as well. Her heritage remained a secret, even to her father (Imalga seduced him in disguise). The only indicator of the girl's heritage were her bright, purple eyes, which she passed on to all of her daughters. The worm that held Imalga's spirit died, then grew again within each new daughter for every generation. In the present day, the carrier of the worm is Nairine Voluman, the daughter of the Headman of Spiralstone Village, not far from the Elderstone Islands. If she were ever brought in contact with the Black Tide, Imalga would be revived (likely killing Nairine in the process).
Hundreds of years have gone by, and it would seem that Imalga's plan for revival is doomed to failure. Her monstrous followers have lost all trace of her offspring, believing them dead. Although they successfully preserved the witch's remains in the form of the Black Tide algae, they don't know what the next step is. Many believe that their master's heart is still intact somewhere (this is false) and have been searching frantically for it. The deciding factors in the return of Imalga have been her two sisters, Aveldine and Thorse. The other two Hags were by no means friendly with their sister. They were essentially slaves to Imalga when she was at her strongest. They were bound together by a complex web of magickal oaths, the most powerful being their Coven Seal. This was a geas that bound the three of them to meet every 99 years and renew the rituals that made them immortal. Part of their agreement was to revive Imalga if she were ever killed by natural means, as it was her power that fueled the spell. If they ever failed in this duty, they would suffer a terrible curse, and a slow painful death.
Aveldine and Thorse naturally panicked when Imalga was finally killed. The curse of the geas quickly took effect, not to mention that they had become the next targets of the Crimson Coil. Rather than honor their oath and revive their sister, they decided to escape to the only place where their sister's curses wouldn't affect them, the home of their mother. Chthondryse resided in a magickal realm that was separate from Pelagia, the Pit of Abhorrence. Aveldine and Thorse took refuge there for more than 300 years. Conflicts with their cantankerous mother, and the other denizens of the Pit, eventually forced them out, back into Pelagia. At that point they had no choice. They had no way of unraveling the geas, as their power was too weak. They had to revive Imalga or die slowly and painfully. They made use of some powerful scrying magic, and eventually learned about Nairine and what was left of Imalga's body (the Black Tide). Aveldine set in motion a plan to invade Spiralstone Village, kidnap Nairine and a number of other sacrificial victims, and perform the ritual of resurrection.
The players are residents of Spiralstone Village, many of them probably being childhood friends of Nairine. The events of the story begin with the village coming under attack by monsters, and Nairine being kidnapped. The players will, presumably, want to rescue her, or at least get revenge on the Grindylows and other monsters that attacked their community. They will follow the trail all the way out to the Elderstar reef, but one way or another, they will not be able to stop Imalga's revival. If they arrive in time, they might be able to save Nairine, and possibly defeat Imalga's incarnation (slowing her down considerably and making future battles easier), but the witch's followers have too much of a head start, plus Aveldine is overseeing the operation personally. If the players find some way to overtake the kidnappers, she will step in. Though she suffers from the effects of her sister's curse, she is still more than a match for low-level adventurers.
From there, the PC's have to do everything they can to learn about Imalga, the Crimson Coil, and how they defeated her in the past. They will likely visit Athune to commune with the Vision Reefs, possibly visit the Sea Elves of Kyrene Bay to learn what they know. They have the option of exploring the Shrine of Davoral, which houses the Tomb of Khozed Thross (and a valuable summoning ritual). They could also visit the Sahuagin city of Athalfar to recover the Blade of Daganys, a weapon that proved most effective against the witch in the past. Once Imalga is revived, she will start moving on her own (more about that later), and Aveldine and Thorse have little choice but to help her with her plans. If the players were to approach either of the other two Hags, they would be open to betraying their sister, but the PC's would have to do most of the work in unraveling their magickal bonds. Another good idea (once they're strong enough) would be to visit the Pit of Abhorrence and ask for a boon from Chthondryse. The Mother of Monsters is not exactly feeling kindly towards any of her three daughters, so she would be open to negotiations. While they ready themselves for a final battle, Imalga is not sitting idle.
(NOTE: Imalga has returned from death, and been reborn from a worm, and as a result she is COMPLETELY insane, and doesn't approach her situation logically). Here is the timeline for Imalga -
One: She returns to her former lair, which is unfortunately where the Alchemist's village of Shoronoe is now located, she bolsters her defenses there, and turns everyone in the village into mindless tunicates.
Two: She flexes her muscles and attacks a few other outlying settlements from Shoronoe, using the Black Tide again as her primary weapon. She tried to do this secretively, but the players might find out if they have their ears open.
Three: She begins to secretly infect agricultural villages and even migrating fish-herds with her algal plagues. Sickness starts to spread around the North, undead are on the rise.
Four-Six: In no particular order, Imalga starts a campaign of revenge in which she defiles tombs and monuments associated with the heroes of the Crimson Coil. She also makes a point of hunting down known descendants of the heroes. This can offer the players some good chances to run into her personally during their own adventures. She will likely visit Laneir's Grotto in Kyrene Bay's kelp forests, the Shrine of Davoral, Arrluk's Monolith in the farther North, and even the Sahuagin city of Athalfar. Once the players are strong enough (they may not know everything they need to), Imalga will attack the Athune Reef City itself. If the party manages to thwart her early on, their final showdown with the witch will likely be in her cavern near Shoronoe. But if she continues unabated during this whole time (roughly eight to ten months sounds good) she will envelop Athune in the Black Tide, and release a horde of monsters and undead into the city.
The witch will not be defeated easily, in the end. Imalga may or may not confront the party several times over the course of the campaign, but she will not be at full strength. She will not even be able to manifest her body completely, so she technically can't be killed, just slowed down. In the end, she will be forced to remove the PC's, so she will risk fully manifesting so she can use all of her class abilities and natural attacks. The same tactics the Crimson Coil used can defeat her, but she has taken a few extra precautions this time. Cutting out her heart will have no effect this time, she must be fully isolated from the rest of the Black Tide, then somehow destroyed on a massive scale (disintegration should do the trick). This is because she was reborn from a worm, so she technically has several hearts. ALSO, while she doesn't have any hidden phylacteries or horcrux-type things, she does have Nairine, assuming she survived Imalga's rebirth. If she is destroyed, she can use Nairine again to be revive herself, as the worm always reproduces before it grows to the next stage. This is bad for Nairine, but there are a few solutions for her. Any of the other Sea Hags, including Chthondryse, can remove the worm safely. The angelic spirit summoned by Thross can also cure her, but this may limit the amount of boons the players can ask of the spirit (it could, for example, kill all the traces of the Black Tide again, or help with Imalga).
However they do it, the players will become the new heroes of Athune and the Northern Reach if they are successful. If Imalga had won, she would almost certainly have conquered the North again, and destroyed the dreams of those who worked so hard to build it up. The players may want to continue their crusade and defeat the other Sea Hags in the wild, or they may be in serious debt to those same Hags, especially Aveldine and Thorse. The party may have also triggered a war with the Sahuagin, promised to go on some ridiculous quest to the Abyss on behalf of the angels.
