Hello fellow homebrew writers.  I heard the word Leviathan used in a conversation today and thought that would be a great focus for a campaign theme.  Of course a leviathan campaign would have to include a dragon or wyvern at some point, but that can't be the last step in the campaign if a level 20 character is supposed to be able to deal with demi-gods and plane travel.  So the encounter to take down the dragon would probably come after level 12 so I need to map out a theme to get the party to this encounter and then figure out where they go from there.

I am thinking of this project against a templet of The Fellowship of the Ring with the early encounters pointing ahead to themes that come later.  I figure a thematic encounter before the encounter with the dragon will be with a dragon cult leader.  Being a campaign theme for dragons, Dragonborn will have to be central to the action.  I am thinking that dragonborn will be at the center of the evil activities but a few dragonborn will be the key figures leading the downfall of Leviathan.

Would anyone like to jump in with an encounter idea building on the notion of a Leviathan campaign?

I think I will plant the seed of the campaign early by having a party member acquire an ornately carved wyvern in stone, a carving about the size of your hand, and have an NPC tell them that is the symbol of "Leviathan."  There is a lot of mystery about Leviathan but some folks think it is a cult and some think it is a dragon and some think it is a old wives tale and so on.  Characters they meet after that will give them information about Leviathan and every time they advance the plot they fall into a handsome reward of treasure.

Thanks for your ideas.

You say Leviathan.... I think of the first two Hellraiser films and the "God" of the cenobites that sits at the center of a labyrinth, maybe have a  cult of leviathan worshippers that use the wyvern/dragon statues in a similar way to the film using the Lament Configuration Box, its a puzzle that opens up a portal and allow travel from one realm to another but once opened the portal is two way so creatures (half Dragons/Dragonborn instead of Cenobites) from the other realm can enter the material plane as well.

Maybe have Leviathan as the name of a prison, created by Bahamut (The Platinum Dragon)  where Tiamats mightiest champions/off spring are held prisoner, the dragon born want to release it but need to find all the statues to open a portal large enough for the prison to enter the material realm where it will open and release the offspring.

Hmmm. Leviathan to me doesn't say dragons at all. Leviathan says a sea-based campaign with Krakens and sea monsters and such. A great time to break out that Triton character you've been thinking about. :)

I would suggest you take a page out of Shadow of the Colossus if you are trying to make the players fight giant monsters. Other than that I would suggest you create unique monsters that fit the playstyle you want for your story.

Leviathan brings to my mind Judeo-Christian imagery. In Jewish tradition, Leviathan is depicted as female, and seems to either be interchangeably known as Tiamat, or is a companion of Tiamat (admittedly, Jewish texts are not my expertise). Leviathan is described as a giant fish rather than a snake or a dragon (meaning it's kosher), and is destined to be feasted upon at the end of the world.

Christian texts are a little more straightforward about it, and I'm way more familiar with those anyway. Leviathan makes a brief appearance in the book of Job, along with Behemoth. The two seem to hang out together wherever they show up, here on planet Earth. In the Bible, Leviathan is described as much more dragon-like, and some people infer that maybe the passage was describing some sort of extinct crocodilian. Medieval texts and supercrazy hell-happy artwork use Leviathan to depict a sort of hellish avatar of greed, and is sometimes referred to as the Hellmouth, cause he's pretty commonly seen just absolutely going ham on scooping the souls of the damned into his facehole. 

So to me, this sounds like your PC's are taking a field trip to the hells. Leviathan can also be used to describe basically any giant sea monster though, a la Moby Dick, and would make a totally sick warlock patron no matter where you decide it lives. If you go the crocodilian route, maybe look into animal symbolism/totem animal meanings and homebrew some sort of brutal druidic crocodile cult, or a crocodile totem for a barbarian tribe. That would also allow your players to fight lower level bad guys on the way to whatever sort of horrorshow you have in store for them :) happy writing!