"Scaly" opponents that make sense in 100-years old dungeon?

[HoboKnight]

Hey guys,
in my campaign, I have a city, under which there is a massive dungeon. For years, adventurers would enter it, only to die there or return running. Parties were up to lvl 10 and entry to the dungeon was eventually sealed off and was now untouched for about 100 years.

The dungeon in question was long ago part of Scaled ones empire and got eventually populated by really nasty things that do not venture onto the surface, but grind pretty much anything that comes in and is up to lvl 10. What kind of monsters would in this case make sense? One way to go about it would be that all inhabitants eventually turned undead. There might be some ancient Scaled ones' guardians like golems. Perhaps a special and powerful monster has made its lair in the dungeon?

TBH I can just populate it myself, but giant always has some really cool suggestions (and completelly new monsters), so I check up on you again :)

Thanks!

[Mastikator]

What is a "Scaled one"? Yuan-ti?

Nevertheless I can think of one thing that ticks the boxes of "doesn't like the surface", "can persist in sealed a dungeon for 100 years", "kills adventurers up to level 10". And that is.... (drum roll please)

Shadow!

Shadows deal strength based damage, so your level won't save you, and if you die from a shadow you become a shadow. So they are very difficult to defeat through attrition, since any failed attack against them just reinforce their numbers. They also have sunlight weakness and won't want to find the surface, and amorphous trait can be defeated by sufficiently tight seals.

You can throw in specters, wraiths, poltergeists and banshees to spice things up. Also ghasts since they can create ghouls, and they can be terrifying in large numbers due to paralyzing attacks. Undead that create undead and use "unfair" tactics (hit-and-run through walls/floors, insta-kill, paralyze, ability score damage).

[J-H]

-Undead
-Oozes
-Dragons or draconic creatures, possibly having hibernated or been in some sort of cold-blooded torpor while the dungeon was closed up - assuming you're doing the "But what did they eat?" approach to make it make sense
-Advanced funguses, molds, rot grubs, etc.
-Aberrations, as they may not age (beholders, starspawn, cloakers, , gricks, grells, other weird and mutated stuff with too many eyes or limbs like the gibbering mouther/shoggoth)
-Fiends & Elementals, potentially summoned/re-summoned automatically
-Anything sufficiently cold-themed
-Gargoyles and animated statues of various types
-Golems, and animated/clockwork armors
-Xorns & Basilisks (they eat stone)
-Plus whatever broke into the dungeon from below and set up a colony of their own (drow? duergar? svirfneiblin? myconids from the underdark? azer/salamanders?)

[Unoriginal]

Hey guys,
in my campaign, I have a city, under which there is a massive dungeon. For years, adventurers would enter it, only to die there or return running. Parties were up to lvl 10 and entry to the dungeon was eventually sealed off and was now untouched for about 100 years.

The dungeon in question was long ago part of Scaled ones empire and got eventually populated by really nasty things that do not venture onto the surface, but grind pretty much anything that comes in and is up to lvl 10. What kind of monsters would in this case make sense? One way to go about it would be that all inhabitants eventually turned undead. There might be some ancient Scaled ones' guardians like golems. Perhaps a special and powerful monster has made its lair in the dungeon?

TBH I can just populate it myself, but giant always has some really cool suggestions (and completelly new monsters), so I check up on you again :)

Thanks!

Could be fun if there was only one real opponent.

Like there is one Skull Lord made from a Lizardfolk swordsmaster, a Kobold Sorcerer and a Yuan-ti spy, waiting in their throne room, guarding the empty tomb of a reptilian god.

The rest are just undead minions and maybe a few surviving constructs, but there aren't many of them.

So the PCs just descend in the dungeon, which is completely bare and silent for most of its perimeter.

EDIT:

Alternatively, you could go for one Eidolon with several (6 to 8) Sacred Statues, representing the dead empire's pantheon.

Might need to max the Eidolon's HPs, still.

[HoboKnight]

Amount of my satisfaction with these answers is so big, it's difficult to describe! :D

[LibraryOgre]

Tortles. They went into hibernation when they were sealed away, living on vermin that made it in.

[Psyren]

What is a "Scaled one"? Yuan-ti?

I'm guessing closer to Sarrukhs, their far more powerful ancestors/progenitors.

@OP: Seconding the undead suggestions, they're a staple for any kind of ruin or buried complex. You also can't go wrong with aberrations, elementals, constructs, imprisoned fiends etc. Even something like a subterranean dragon may have taken up residence.

[Dualight]

A dracolich would probably fit. Undead, so 100 years is nothing, and a dragon, so it should still have some scales left. It is also powerful enough that low-level adventurers are doomed if they run into it. It also retains its Frightful Presence from when it was alive, so even the courageous can be reduced to terrified wrecks.

[KorvinStarmast]

Tortles. They went into hibernation when they were sealed away, living on vermin that made it in. It's tortles all the way down. The Horror!
A dracolich would probably fit. Undead, so 100 years is nothing, and a dragon, so it should still have some scales left. It is also powerful enough that low-level adventurers are doomed if they run into it. It also retains its Frightful Presence from when it was alive, so even the courageous can be reduced to terrified wrecks.
That was my idea, but add in a few mummies and the undead mentioned above.

[Mastikator]

The dracolich makes a lot of sense. It's strong enough to be a warlock patron (undead), so you could throw in a cabal of deathlocks and maybe a skull lord that serve the dracolich. They then populated the dungeon with undead and help convert dead invaders adventurers into more undead.

There could've been a ploy a long time ago, when the dungeon was first built it was designed to be the scaly one's empire treasury, but it turned out to just be a ploy to transfer all of the empire's gold to the dracolich. The scaly ones tried to reacquire it but were slaughtered and undeadified. People kept trying for a while and eventually gave up, they just sealed it up. Then people forgot and unsealed it, because maybe there's gold in there?

[Wintermoot]

Sleestak. If they are kept cool enough, they will just hibernate with no degradation until heat wakes them up.

[Leon]

"Sealed" insofar it was sealed at one end 100 years ago and unless someone is checking those seals it could well be unsealed/ broken into from another end

[Kane0]

Kythons. Demon-lizards. Smart, plentiful and increasingly powerful as they grow. The kind of thing you dont want to let incubate over 100 years...

[MagneticKitty]

revenants can't die until their mission is done, they can be anything formerly humanoid and could be fun.
make them yuan ti, dragonborn, lizardfolk, whatever
could also use revenant as a template and throw its abilities (but not stats) and creature type onto any existing humanoid stat block
these are good choices if you want sentient things instead of mass unintelligent undead.