I'm trying to design a temple to a storm 'god.' In my pantheon, there was a war between two factions of gods, and the losing side was imprisoned. Except for one who fell in love with a god from the winning side who used their influence to keep the god from the losing side from imprisonment. 

So the storm god has a bad relationship with the other gods, who want to throw him in prison. Problem is, he usually hangs out with his godly wife/girlfriend (She doesn't like labels) until she needs some space. Then he runs around the world, bringing storms and playing keep away from the other gods. He's really good at avoiding them at this point and has been free for millennia.

This causes some issues for mortals who worship him as the other gods think he's a miscreant. So it's more of a secret society. He has a few temples built for him but they're out in the boonies. 

At the time of the campaign, the godly roles have been reversed, and the losing gods are freed and the winning gods are imprisoned. Except for the storm god, who is disliked by both sides and is VERY good at avoiding being caught. The party needs his help in their coming up quest line, and will go to his temple to try and communicate with him. Unfortunately, there has been a trap laid for him and the party is going to finally get a peek at the bigger picture of the campaign.

The crux is this: I'm having the damndest time figuring out what goes in this temple. I imagine it as a tall structure, with multiple levels extending into the sky. Certainly a level honoring the dead who served the storm god, a level honoring the goddess wife/girlfriend, a level honoring the storm god. What else? I don't need it to be heavily logistical (Where do the workers sleep? Where do they eat? How do they get supplies? Who has been doing the laundry?) but I do need some level of... world building, I guess? 

The mood of the campaign will shift when the party arrives at the temple. It's been pretty light and jovial up to this point. The enemies joke when they fight and some pop culture references are made. I want them to show up and it be dead quiet. There's a small welcoming desk but it's abandoned. Crystals embedded in the walls flicker with dim light, like lightning flashes making a last surge before disappearing. Orderly trails of dried blood coat the floor, and it seems like bodies have been dragged from the rooms to a central location farther in the temple. There are a few medium-tier enemies who I imagine as inactive mind-controlled demons who react to the party's presence. There are a couple each floor, and they have shared vision. Defeating one or two of them isn't much of a hassle for my party, but ten of them will certainly be deadly. So they're on the clock to kill them before reinforcements arrive. The party explores the first floor, which is a complex dedicated to the honored dead of the storm god. Some zombies and skeletons with lightning flair would be fun to put here. Second level dedicated to the goddess who is kind of a barbarian/ranger mix; a patron of wild things and places. Third level to the god himself, and the fourth and up levels pending community ideas. The final level is a roof exposed to the sky and a large lightning rod as the main attraction.

My issue is coming up with optional/extra things in the areas. I can throw in encounters as much as I want, but I want something for the party to explore. Maybe some low level random table magic items. I want this location to flush out some lore and some godly backstory, and I'm having issues on that front. Typing this all out has been helpful, but any input or questions from other DMs would certainly be welcomed. 

The first thing that comes to mind as far as an area is the main worship area where the gods' followers would go to try to commune with him while in the temple.

Typically, the dead are buried in catacombs beneath a temple. If thematically you want any who enter the temple to be intimidated/scared, then go for it with having the dead on the main entry level.

If you have the blood trails leading in an obvious path, I don't see any party being like "Let's explore these rooms that don't have blood leading to them."

In my head, I see the first level being where all the logistics that you want to hand-wave away would be housed- the kitchens, the supply rooms, the living quarters for those dedicated to the upkeep of the temple and to the god's worship. Iconography everywhere, some images devoted to the honored dead, some to the one who kept him free, some to him.

Second level, perhaps this is where the head of the temple lives and works. Has s/he been killed and turned into an undead creature put here to stop any who would interfere? More iconography is everywhere in this temple.

How many levels are you thinking? What's the trap set out for this god? Is it set to only go off if the god enters the temple in a corporeal form? Or is it possible the party will set off the trap? How complex is this trap? Can it be deactivated by the party if they are investigating for traps?

I see the final level as being where the main worship takes place. This is a temple devoted to a storm god. Open-air worship with a lightning rod to attract the god's gaze makes sense.

Oh what excellent questions.

Death in this world is more of an oddity than a scary thing to be avoided. Most people get into whichever gods' 'heaven' and if people died before their time they would be easily resurrected. The gods had a very heavy hand in the development of the world and really coddled the races. So the dead would be more of a kind of museum display over a tomb. 

The trap set for the god is to tire him out and exhaust him. His normal state is relaxing or hiding in the big forest with his wife the goddess, and then occasionally he will sprint around and dodge the other gods. He's not one for marathon running. At this point, the gods have been imprisoned for nearly 4 weeks, and he's been on the run the entire time. All other temples and locations of rest for him have been effectively shut down, so the only place he can possibly try to get some rest is this last temple. When he touches down, he'll be run ragged and easy pickings for someone with the know-how to trap him. There is a more direct puppet of the BBEG's who is heading this operation at the top of the tower. The trap is less physical, able to be disabled one and more intricate plan. 

To multitask and kill time until the god arrives, the BBEG puppet will be having his lesser puppets collect the (recently) dead of the temple and performing a ritual to turn them into more puppets. This will occur at the top of the tower while waiting for the god to crash down. This could be where the temple leader is turned against the party, but they don't have any connection to them so it won't be a big personal affront. 

Do you intend for the party to be strong enough to change the course of events here, or is trapping the god going to be a sure-thing? To my mind it kind of affects how the temple will play and how you plan the top-level encounter. If the party might be able to influence events then you obviously have to plan for them to have some resources left, but if they're not going to be able to do anything about it then they could show up completely tapped and it wouldn't matter, giving you more freedom to plan elaborate trials through the different levels of the temple.

On a related note, this temple is calling out for a Storm Giant Quintessent serving as the guardian of this temple, and you can have it help or hinder the characters/BBEG depending on what suits your needs. I picture an ever-raging storm all around the temple, which doubles as the Quintessent's lair, meaning it can fade into the storm and reappear anywhere within it's lair it chooses, so you can have the characters encounter it multiple times throughout the temple and it can either be helpful or dangerous depending on which side it's on.

If this is his last temple, then it's going to be well hidden. Even out in the boonies, I'd be surprised if it was some giant tower, that's too attention grabbing. I'd suggest something that goes into the ground, where it's less obvious. Maybe even inside a mountain. The entrance can be at the bottom or the top, but the entire structure would be carved inside of the rock. I would see at least a level or two populated by elementals, both air and water would work if they are working for him, but if they are traps laid by enemies, then earth.

A better option might be for it not to be a building as much as an area. The storm god would want to be out in the open under the sky, where people, and he, could feel the power of his domain. The god of storms isn't going to go behind walls and hide from the weather, he'll revel in it. He won't want to be worshipped inside, where his clerics (I'm assuming tempest) can't cast call lightning. He'll insist they feel the rain on their faces while they pray to him. So it would be more of a hiding in plain sight kind of thing -- which is why he's been so hard to find, he doesn't confine himself to permanent buildings like the other gods. The last refuge isn't a building, its a small town (20-30 people) who all secretly worship him. I could see farmers paying him service because while they want rain, they don't want too much rain, or hail or tornados for that matter, so it could be on the plains somewhere. Also coastal areas, where fishermen fear hurricanes, could work. Then different areas in the region (or within the town) have different features that correspond to the things you are discussing. Depending on his lover's domain, maybe she has a shrine or a temple set up somewhere. To me, the way to tire the storm god would be to deprive him of storms. Make the weather really dry, almost desert like, or just clear blue skies without a cloud to be seen, deprive him of his function. If you can wait a couple weeks, you might use the Tasha's rules for supernatural zones. Not that I've seen them, but those seem to fit with it, if you go with this idea.

 IBernstein, that storm giant is a brilliant idea. It would also help to solidify this new mystery enemy as resourceful and powerful. 

My ideal situation would be this: Upon arriving at the tower, they see the landscape is trashed. Trees have been ripped up by their roots and craters dot the area around the tower. The tower is around 50 feet tall, and with a low DC perception check they can see The Storm Giant dangling from the side of the tower bound in chains. The party climbs to the top of the tower, a little worse for wear but not on their last leg. They have faced mysterious new types of enemies that seem to be corrupted demons, but what could corrupt demons? A gentle rain falls and flashes of lightning are weak and somehow to thunder feels... quiet.  There they see a creature poised to strike at the base of a lightning rod but he is unmoving until the party catches his attention. There is a massive iron spike driven into the floor through the links in a giant chain hanging off the side. 

The creature stirs and glances at the party. The thing is nearly human, wrapped in bloody chains. Now that they've seen the party, the chains move and twitch like a multitude of tails on a cat. The party may ask some questions of it, but it mostly reveals that it had assumed the hardest part of capturing the god would be the guardian storm giant, so its more powerful asset left the scene. It is surprised that any of the gods' creations would be able to continue living without the continued hand-holding of the gods. If the party had snuck by the lower puppets in the tower, they can make their way up the stairs to the roof over the course of the combat. If not, then the creature can realize that its lower puppets have been destroyed and give the party a small bit of respect for surpassing their low expectations of the mortals in this realm. There is the option of freeing/healing the storm giant, but that would be more of a wild card than a boon to the party. I imagine the giants freaking out and just wiping everything it can out to protect the god. 

I want the party to learn that there is someone pulling strings to accomplish an unknown goal. That person can somehow control bodies, and now they know that the party is capable of interrupting their plans. 

Xalthu, I wouldn't say it's a giant tower. But also civilization is hedged tightly to the cities, and a lot of the continent is wilderness. The gods are more concerned with growing and refining and perfecting their cities more than expanding them.