D&D 5E Expanding Wave Echo Cave to bring PCs to 6th level

[Agglomérante]

I'd love to know what ideas others have for extending Wave Echo Cave. PCs are expected to be 5th level upon completion of Lost Mines of Phandelver (LMoP). I have a party of six PCs I'd like to raise to 6th level by extending the map of Wave Echo Cave.

I was thinking it might be fun to radically extend the map with an ongoing mining operation of skeletons and other undead on auto pilot, overseen by the Spectator -- who in the adventure is said to believe the mine is still functioning. It is. There's a functioning magical smelter, designed by the gnome wizards for (in part) longevity. Next to the smelter, all the by-product of that smelting (slag) is conveyed to a stationery sphere of annihilation, designed by the human wizards. Convenient, no? I figure it's not a stretch to find such advanced magical mining assets at the same location as the legendary Forge of Spells. There might even be a modron tasked with keeping the smelter in working condition.

There's a Heavy-Metal-scale-fantasy hole dug in the earth, as the skeletons have been chipping away at hard stone for hundreds of years, hauling it back to the smelter. How long the operation's been running depends on how long ago the denizens were transformed into undead.

The ongoing smelting is also done on undead auto-pilot with a hint of intelligence, producing the poorest qualitymetal (whatever it was they mined) anybody's ever seen. A mountain of stacked metal broods over a quarter of the cavern, with a ramp of stacked metal leading up its side. Gundren Rockseeker and co. need only re-smelt it to be rich, nevermind the Forge of Spells.

So it's more skeletons, ghouls, ghasts and maybe a spellcasting wight or two acting as foremen. That probably doesn't bring me to the xp total I need.

I figure it might be fun if the mining operation recently opened a hole into an underground cave complex, which allows for water and fungi/mushrooms and critters! A mine is so sterile that it's hard to populate with monsters.

How would you extend Wave Echo Cave?

 

[S_Dalsgaard]

My plan was to let the PCs explore the lake in the upper right hand corner of the map and have it lead to a larger cave complex, maybe even with access to the Underdark.

 

[Jaelommiss]

Ever since seeing that map I've wanted to add a dwarven tomb to it somewhere. It'd be largely full of skeletons and zombies. Three separate crypts would be at the end, each containing a mummy (former king), a few supporting undead, and a chunk of treasure. Each of the three mummies would have slightly different abilities (one cleric, one fighter, one sorcerer).

 

[Agglomérante]

Those are both excellent ideas. Love the three specialist mummies.

There are fantastically-imagined encounters for both those ideas, including dwarven submarines and dwarven crypts, in Raggi's "Hammers of the Gods." Here are some excerpts:

A purple mist floats from underneath the crack in the door. The door is
easily opened, and doing so will reveal a thick purple mist filling the inside
hall.

This mist is about knee-high on a human, and fills the entirety of the entry
hallway and locations #2 and #3. It is not harmful in any way, but obscures
the floor completely. Its purpose is to preserve that which it covers. Even
though it will spill out onto the surface after the entry door is opened (and
into other areas as those doors are opened), the mist will never seem to
thin out or dissipate from the interior of the dungeon at all.

Anyone entering the chamber, if all else is still and quiet, will hear
whispers in the air, seemingly coming from just far enough away to not
be understood. Dwarfs, or any with any functioning sensory magic (such
as any Detect spell, Clairvoyance, etc), will see the air in the chamber
filled with spirits of restless dwarfs, flitting this way and that, screaming
“Why?” at the bodies below.

The cranes are seventy-five feet tall, supported by a stainless steel lattice
tower. The booms extend thirty feet. The hoist line for each crane is made
out of fifteen hundred foot long thick steel cable. Each crane has a control
box on top in which manual cranks allow the cranes to swivel back and
forth, as well as extend and retract the cables.

Do note that these towers are far taller than the range of torches and
lanterns, so adventurers will only see the bottom of the tower, and if they
are some distance away also the cables dangling from the sky. They will
have to climb to discover more.

The adventure doesn't work as an extension to the map but parts of it could be lifted for sure. I'd been weighing whether or not to run it as a whole, but hadn't considered just lifting some rooms. Raggi's got inspiration.

 

[Nebulous]

I thought of adding the Seven Pillared Hall from Thunderspire Labyrinth.

 

[Agglomérante]

I thought of adding the Seven Pillared Hall from Thunderspire Labyrinth.

I actually own that one.

It would be tricky connecting the map. You have to keep the Lost Mine of Phandelver actually lost and undiscovered. If it connects to civilization underground, it's only ever just on the other side of that collapsed offramp.

The mining skeletons from my scenario could have dug deeply enough in 500 years to break through to the underdark and something like the Seven Pillared Hall. Miles of digging.

Come to think of it, the mining skeletons could emerge in all kinds of weird places. Tomb of Horrors, lol. Dark Tower! oooh. Skeletons begin carrying back smashed furniture rather than just rocks to the smelter.

 

[bolo__]

Check out Scrivener of Doom's stuff at http://my-realms.blogspot.com.au/?m=1

 

[Unwise]

The skeletons on auto-pilot take the finished metal into the storeroom/treasury. Bad news for the PCs is that when they get there they find the mother of all Rust Monsters and her brood. Having an endless supply of metal fed to her has made he huge and lazy, a fight well beyond them but easily avoided, unless they want her 'horde'. Her children however and less easily avoided.

Bullettes/Umberhulks could also be included in order to make tunnels into the complex. This then allows for a sensible reason for creatures like the Rust Monsters or any underdark horror to have found their way into the place.

 

[Nebulous]

I actually own that one.

It would be tricky connecting the map. You have to keep the Lost Mine of Phandelver actually lost and undiscovered. If it connects to civilization underground, it's only ever just on the other side of that collapsed offramp.

The mining skeletons from my scenario could have dug deeply enough in 500 years to break through to the underdark and something like the Seven Pillared Hall. Miles of digging.

Come to think of it, the mining skeletons could emerge in all kinds of weird places. Tomb of Horrors, lol. Dark Tower! oooh. Skeletons begin carrying back smashed furniture rather than just rocks to the smelter.

Not necessarily. It might only be *lost* to the surface world, but some of the denizens of the Seven Pillared Hall might know of its significance, but opt to keep that knowledge hidden anyway. Besides, as you mentioned, you can have them miles and miles apart. Twenty miles in the Underdark might as well be a thousand miles on the surface world. I like the skeletons idea.

Anyway, i don't know if i'll do it or not. Part of me really wants to go homebrew on the last part of Phandelver, but part of me also wants to run some classic D&D modules like Ravenloft. There's just too many options, and all of them good ones, and only limited time.

 

[The_Gneech]

I basically set it up so that Wave Echo Cave was actually a side-level to a larger, Moria-like complex centered on the underground lake. There used to be passageways connecting it to the larger complex, but they all collapsed in subsequent earthquakes. To get the players interested in braving the lake to get to the other parts, I've included a large overview map of the complex, which includes "The Greater Spellforge", an enormous arcane furnace heated by lava flows from under the volcano.

-The Gneech

ETA: Oh, and yes, I connected mine to Thunderspire Labyrinth. The northern portions of Phandelver are actually the duergar portions of that setting in my game, although I've completely retooled it from the 4E version (basically a remake keeping the core story elements and throwing out the rest).