D&D 5E An Endless Stream of Monsters!

So, as I mentioned in another thread: I'm building a megadungeon based on a couple ideas. One of my players, when he tried DMing, began running a campaign based on an anime about a sadsack adventurer who tried to make his fame - and win the love of some great adventurer - in a megadungeon under the city. Success is measured by reaching lower levels of the dungeon, by beating boss monsters, etc.

So: delving as a sport, delvers as professional athletes.

To make this make sense - to have some vaguely logical reason for why the dungeon always has monsters despite adventurers make multiple delves every day - I've decided the dungeon naturally repopulates itself through what I've dubbed "spawn engines."

After inventing a few spawn engines, I've found the idea is proving awesome. By figuring out why a spawn engine exists in the first place, the dungeon itself gets reshaped and flavored in ways I wouldn't have otherwise considered.

For example, the top levels of the Dungeon are populated primarily by a spawn engine called The Imp Portal. It's actually two portals - to Hell and the Abyss - spewing out endless demons and devils who are playing a constant game of King of the HIll with each other. Each day, a new Boss, with minions, comes through the Imp Portal to challenge the current Boss and its minions. So whenever the players are in these levels, they can find various situations, randomly determined: The Bosses might be battling each other, or preparing for the battle, or celebrating their victory. And there's a new Boss every day!

Another spawn engine is the rather undefined "Fey Caverns." This is a point where the Feywild intersects with the dungeon, where various plant monsters can grow in seconds. Think the Genesis Cave from the Wrath of Khan . . . and I'm now renaming this engine The Genesis Cave.

There's also some weird, massive magic crystal that stretches through several levels of the dungeon. It spawns crystal skeletons with coins or gems in the eye socket. And they're powered exactly as you think they would be: Copper-eyed skeletons are super weak, diamond-eyed skeletons are Badass Bosses.

Anyway. My creativity only stretches so far, and I'd appreciate more ideas for spawn engines I can build from.

What are the coolest or craziest way to spawn monsters?

A couple off the top of my head:

• Some kind of huge bloated broodmother spawning aberrations. It's far too big to fight conventionally.
• The entire level is trapped in some kind of time loop. Every 24 hours, everything in it (including the monsters) resets to its original state; adventurers who don't get out before the reset will be trapped in the loop potentially forever.
• Similarly, a planar rift to the realm of Ysgard. Each dawn, everything that died in the area returns to life to rejoin the endless battle.
• The level is suffused with negative energy in a way that animates loose bones and knits them together into strange, mismatched skeletons. When two of them fight (which is often) the winner draws the loser's mass into itself and becomes even larger. The end result is an undead mockery of an ecosystem, with monsters ranging from huge, ancient bone-titan predators to tiny bone-shard swarms.
• A living Animate Objects spell wanders the dungeon, turning everything it encounters into constructs.
• Far across the sea, in an empire peopled by one of the monstrous races (goblinoids, let's say), there's another, similar dungeon. Goblinoid adventurers delve their dungeon the same way humanoids delve this one. The depths of each dungeon connect to the other via extradimensional pathways. The goblinoids have no idea what's spawning all these humans in their dungeon... but since the humans have some great treasure (weapons, armour, magic items) and are apparently in endless supply, there's never a shortage of new goblinoid adventurers ready to seek their fortune against them.

There's actually an entire RPG set around this idea. Xcrawl by Goodman Games. You can pick it up on DriveThruRPG or their site.

Igfig said:

A couple off the top of my head:

• Some kind of huge bloated broodmother spawning aberrations. It's far too big to fight conventionally.
• The entire level is trapped in some kind of time loop. Every 24 hours, everything in it (including the monsters) resets to its original state; adventurers who don't get out before the reset will be trapped in the loop potentially forever.
• Similarly, a planar rift to the realm of Ysgard. Each dawn, everything that died in the area returns to life to rejoin the endless battle.
• The level is suffused with negative energy in a way that animates loose bones and knits them together into strange, mismatched skeletons. When two of them fight (which is often) the winner draws the loser's mass into itself and becomes even larger. The end result is an undead mockery of an ecosystem, with monsters ranging from huge, ancient bone-titan predators to tiny bone-shard swarms.
• A living Animate Objects spell wanders the dungeon, turning everything it encounters into constructs.
• Far across the sea, in an empire peopled by one of the monstrous races (goblinoids, let's say), there's another, similar dungeon. Goblinoid adventurers delve their dungeon the same way humanoids delve this one. The depths of each dungeon connect to the other via extradimensional pathways. The goblinoids have no idea what's spawning all these humans in their dungeon... but since the humans have some great treasure (weapons, armour, magic items) and are apparently in endless supply, there's never a shortage of new goblinoid adventurers ready to seek their fortune against them.

Click to expand...

Oh man, these are fantastic.

The time loop one is absolutely perfect. The threat of being caught up in it is a great touch. And the fact it resets back to a single predefined state contrasts nicely with the random setup I've been using everywhere else.


Thank you.