Mystryl Themed Dungeon

[Xihirli]

Upcoming in my campaign is a dungeon sheltering the remnants of the dead goddess Mystryl.
I want to make this a huge dungeon with a variety of challenges guarding this remnant.
What form this remnant might take is in the air, too. I was thinking either a pendant like what Mystra (a similar but not identical goddess) uses or possibly some sort of spellbook.
The ideas I’ve come up with so far are an encounter in a chamber composed of tourmaline, which reflects any spells that miss their targets or have an area of effect that hits the wall as lightning in random directions.
The other is the final boss being somebody who failed to steal Mystryl’s remnants who was then cursed with several very detailed powers I’m pretty proud of. Suffice it to say I have the final boss ready.
Tl;dr what are some good traps, encounters, and unique features that could make for a memorable “tomb of the goddess of magic” dungeon?

[Rukelnikov]

The second part of my first long running campaign centred around reaching a forgotten temple of Mystryl that layed in ruins in the upper Underdark. It got there after the fall of Netheril, and the final chapters of the adventure took place inside the temple itself. I'll tell about it, and if anything suits you, be my guest and use it! (It was a 3.x adventure, and by the time they reached the location PCs were around lvl 16)

In the bottom of a 1000 ft tall chamber lays what used to be the top part of a Netherese enclave, the area is littered with ruins and covered by an unusual ammount of Faerzress making it a wild magic area and preventing teleportation into or out of it (I think I used a really high DC caster lvl check to allow for tp out, but it was REALLY high).

Within the pink fog that covers the place a timeless battle took place, echoes of a skirmish that took place milleania ago still resonate on the chamber, the Faerzness ghosts don't register the PCs or anything but the echo unless their attention is called and are likely to register anything outside the echo as an enemy.

In the area there were many ruined buildings but four stood out in somewhat better shape, these four buildings symbolyzed the four "points" of Mystryl's symbol, and where there as a clue for the players to look for the temple in the centre of the ruined plateau.

In the centre of the plateau there's a "portal" taking those crossing it to othe temple itself, which lies in some kind of demiplane. To be able to cross the portal one needs to see it, and to see it, one needs to look in the general direction where the portal should be and "will to see it".

Having crossed the portal one appears in the centre of a dome shaped room with a statue of Mystryl, her symbol behind it, and a scroll floating on a pedestal opposite to the statue. The scroll is blank and can fill itself with any religious text of Mystryl (something like a kindle with all of Mystryl's religious text). There's an archway leading to a contiguous dome shaped room, which we will call The Hub.

The Hub is a dome shaped room that contains eight magical glowing symbols hovering about 4 ft above the ground forming a circle, only one face of the symbol's glow (meaning they project light only in one direction, not all around). Each of the symbols corresponds to one of the eight schools of magic*, and the whole room is basically a giant "teleportation" device (the temple itself are a myriad demiplanes that can only be accessed thru The Hub).

Within The Hub spells don't work as they usually do, any spell attempted to be cast inside doesn't have its usual effect but instead a different one depending on the school the spell belongs to. A spell casted will flip the symbol corresponding to its school, so that if it was looking inwards it now looks outwards, and vice versa. If a Universal spell is casted, and the symbols are arranged in a valid configuration, those inside the symbol ring will be transported to the proper destination. If the symbols were not arranged in a vlaid configuration, the system "resets", leaving all the symbols looking outwards. (There are no universal spells in 5e, so something else will have to do, perhaps a couple specific cantrips like Prestidigitation, Thaumaturgy, Druidcraft, etc.)

Valid Configurations:

All symbols looking outwards except for 1 looking inwards: Teleports to the chambers of the Savant of the corresponding school.
All symbols looking inwards except for 1 looking outwards: Teleports to the Infinite Library, the symbol looking outwards determines the section of the library in whichs entrance you appear.
All symbols looking inwards: Teleports to the Gardens.

The Hub was designed as a puzzle, players were not told the symbols represented the schools of magic (they figured that much out very fast though), and weren't told anything about its workings or functionality. They could find out things about it in the scroll in the next room, they could discover it is a teleporter of sorts and it is operated by casting spells in it. Once the players discovered how it worked, they would just name symbol configurations and spend the necessary spells to reach it.

NOTES:
When I ran this, I made the puzzle unnecessarily more complex, a spell would not flip its own school symbol, but the one "spell level" to the right, thinking back on it, it wasn't a good decision

IIRC Netherese used a different division for magic, instead of schools they divided it in Invention, Variation, and something else, which were subdivided further. While using the schools may not be the best representation, it was so that the puzzle wouldn't become even harder. Noticing the 8 symbols corresponded to the eight schools was something that happened almost instantaneously, and allowed for the players to already have a starting point to piece the puzzle together.


I had the idea of basically making a neverending library where anything ever written could be found, but it would be basically impossible to find anything you are looking for unless you already knew where to look. It was kind of a mini dungeon within the temple. I had random encounters in the library, searchers gone mad after millenia travelling thru it looking for some specific piece of forgotten lore . And I used it to place a couple things relevant to some of the PCs, basically it allowed me to place a lot of things in one place if the players decided to look for it. Ancient Techniques on iron folding? It is here SOMEWHERE amongst the gobsmackingly vast amount of books.

The library is a spiraling staircase with doors leading to the different sections of it. Each section is, for all intents and purposes, infinite.

The gardens had a couple locations of interest, a shrine housing a crystal which powered the temple, a small tower atop which the Oracle of Mystryl ("High Cleric") lived. And the encampment of the big bad and its party and minions. Since you already have your BBEG, you should customize the garden to suit that.

[Xihirli]

I like it.
What I’m thinking of doing is marrying the library and the code combination so they have to visit the level of each library to find out the combination to use for the rune room.
Any good ideas on what the school tunes can look like?

[Rukelnikov]

I like it.
What I’m thinking of doing is marrying the library and the code combination so they have to visit the level of each library to find out the combination to use for the rune room.
Any good ideas on what the school tunes can look like?

Perfect, the great thing about The Hub, is that you can just tune it to have as many or as few valid combinations as you like. Having them find said combinations in the library sounds like a great idea!

Google "dnd schools of magic" and check images there's quite a bit very good ones. Checking just now, I liked this one:

https://i.redd.it/kf0xb3u9rgnz.jpg

[Xihirli]

Did you put any cool thematic loot in there?

[Rukelnikov]

Did you put any cool thematic loot in there?

Oh yes, yes I did, and thats one of the things thats remembered to this day lol. In the gardens I put a "magic items museum" of sorts, it was here that the crystal (mythallar) that kept the temple going was housed. There were many items of varying power in display. Once the PCs entered the museum, the BBEG was alerted and combat started. Two of the players spent the first 5 or so rounds of the final fight searching/equipping themselves in the museum lol. That was basically the "hoard" they were gonna get, only that they had it available before defeating the BBEG. Let's say the rest of the party had mixed reaction when 2 of the front liners left their posts to loot and equip themselves mid battle.

In the library I had planned there to be tomes of stats (they only found a +2 Cha one), some scrolls, and books with forgotten/hard to come by lore that gave bonuses to CL when casting certain spells.

If you wanna add some themathic items, I'm pretty sure those guys were big on blast scepters... I don't remember much else right now, if you can check the 3.5 "Lost Empires of Faerun", that had a lot of lore about Netheril.

[Xihirli]

I’m putting some Tomes in the Divination section of the library

Thanks for all of your help!

[Rukelnikov]

I’m putting some Tomes in the Divination section of the library

Thanks for all of your help!

Glad to, happy DMing

[Xihirli]

So as of today my players are facing the final boss of the dungeon, a dragonborn who has become a guardian of Mystryl's pendant against his will upon trying to steal it.
I was going to include some minions for him but along the way the rogue got possessed by Shar (unbeknownst to the party) and dealing with that really makes minions unneeded to divide the heroes in the battle.

What I did instead of an infinite library was eight finite but arbitrarily large libraries corresponding to the schools of magic, and the number of bookshelves was the school's place in the combination needed to get past the Hub. Each library had its own guardian, though they never fought the Transmutation one because an agent of Vecna, also trying to take the pendant of Mystryl, made it through that one before them, and instead of facing the Guardian they had to drive away the agent of Vecna (an intelligence-based warlock with a Shield Guardian), who escaped and plans to follow them after they leave the dungeon.
They didn't ever cast any spells in the Hub, but luckily one of the players missed a session and their character was disappeared for about a day of exploring, so I was able to contact that player. The rest of the party entered the hub from the Abjuration library the next session to find that the previously absent player had apparently led the Conjuration Guardian into the Hub for a fight.
Over the course of the fight many spells were cast and they learned how the runes in the Hub worked, and the wizard player gathered that there was a combination probably based on the changing number of bookshelves.
They did a pretty good job going through it, and I'm proud of them.

I realized halfway through designing it that this was a really good dungeon for one of them in particular - the wizard found so many spells.

[Rukelnikov]

So as of today my players are facing the final boss of the dungeon, a dragonborn who has become a guardian of Mystryl's pendant against his will upon trying to steal it.
I was going to include some minions for him but along the way the rogue got possessed by Shar (unbeknownst to the party) and dealing with that really makes minions unneeded to divide the heroes in the battle.

What I did instead of an infinite library was eight finite but arbitrarily large libraries corresponding to the schools of magic, and the number of bookshelves was the school's place in the combination needed to get past the Hub. Each library had its own guardian, though they never fought the Transmutation one because an agent of Vecna, also trying to take the pendant of Mystryl, made it through that one before them, and instead of facing the Guardian they had to drive away the agent of Vecna (an intelligence-based warlock with a Shield Guardian), who escaped and plans to follow them after they leave the dungeon.
They didn't ever cast any spells in the Hub, but luckily one of the players missed a session and their character was disappeared for about a day of exploring, so I was able to contact that player. The rest of the party entered the hub from the Abjuration library the next session to find that the previously absent player had apparently led the Conjuration Guardian into the Hub for a fight.
Over the course of the fight many spells were cast and they learned how the runes in the Hub worked, and the wizard player gathered that there was a combination probably based on the changing number of bookshelves.
They did a pretty good job going through it, and I'm proud of them.

I realized halfway through designing it that this was a really good dungeon for one of them in particular - the wizard found so many spells.

Great! Have you planned what are you going to do with the pendant if they beat the guardian? Is it gonna be part of the loot?

About the wizard having a good time, well... they ARE going thru an ancient temple of Mystryl so... I think its fitting :P

[Xihirli]

Well, the Rogue possessed by Shar wants to bring it to a vat of dark weave in order to let Shar devour Mystryl's divine spark. The group as a whole was sent in by a gold dragon who was supposed to be guarding the Pendant, but nearing the end of his lifetime has prompted him to desperately seek out immortality. So he wants it to become a god. The wizard wants to bring it to Mystra (Midnight) as the successor of Mystryl.
So they might get it. I expect them to beat the boss, it's the Shar-possessed Rogue after the fight that I'm expecting will give them trouble.

[Xihirli]

They beat the Shar out of the Rogue.

[Rukelnikov]

They beat the Shar out of the Rogue.

Ajajajajaja great, did they get the pendant too?

[Xihirli]

Yes, they have it! And we ended the session right after.