D&D Encounter: The Foul Gate

How to use this encounter

This encounter presents a potentially deadly challenge for four characters of 4th level and will take approximately 45 minutes to run. It presents a dynamic combat encounter in which the characters must close a planar gateway to save a village. This encounter is centered on a village of gnomes called Gulchbar but you can place the foul gate in any other village. As always, feel free to modify, tear apart, or reskin this encounter to fit the needs of your game.

Encounter overview: A deadly cure

The gnomes of the village of Gulchbar have a problem. In an attempt to cure a mysterious disease, they erected an adamantine archway which was supposed to bring healing winds from the Feywild to Gulchbar. Unfortunately, slight errors in the construction have caused the gate to instead summon foul winds from a festering fey swamp in the Feywild. Along with the winds come terrible monsters. Can the characters help the gnomes of Gulchbar?

Encounter hook: HELP!

The characters can smell the foulness coming out of Gulchbar from miles away. Eventually, a gnome scout called Yemorn, riding an axebeak, intercepts the characters and pleads for their help. The characters look like sturdy adventurers and no one else is close, so the party is the only hope for Gulchbar. Yemorn gives the characters the following information:

In an attempt to cure the villagers of a mysterious disease, the master blacksmiths of Gulchbar erected a metal archway which connects to the Feywild. The alchemists of the village promised that with the gate, they could summon healing winds to sweep through the village.
Unfortunately, there seemed to have been fatal flaws in the construction of the adamantine portal. Now, foul winds envelop the village, and terrible monsters have emerged from the gate.
Most of the gnome villagers are too weakened by disease to flee. Disaster is looming for Gulchbar.
If the characters manage to save the village, the gnomes have many masterful artworks and useful items they could offer as a reward.

Running the foul gate: Waves of destruction

A toad that feeds on gnomes

If the characters agree to Yemorn’s pleads for help, and follow the gnome to Gulchbar they find a terrible scene. A 30 ft. tall metal archway belches clouds of green and yellow fog onto a gnome village of tiny houses, empty streets, and deserted shops. Coughs, retching, and screams can be heard throughout the village.

When the characters arrive, they see that a monstrous toad has jumped out of the gate which is erected atop a small hill overlooking the village. A giant toad, overgrown with moss, swallows a gnome who is trying to fix the archway. Chaos erupts, as the gnomes of Gulchbar scramble for safety.

Waves of swamp terror

Once the characters have entered combat with the giant toad, the gate will spit out a new monstrous swamp creature every few rounds. For the first three waves have the next monster crawl out of the gate when the characters are close to beating the creature of the previous wave. That way, the party has to deal with creatures of multiple waves for one or two rounds. The shambling mound (wave four) and the young black dragon (wave five), however, provide enough of a challenge on their own.

To keep things simple new monsters always arrive on initiative count 20, and always act on initiative count 10, losing ties in both cases.

The monsters get bigger and badder as the fey swamp on the other side attracts more and more of them. Here’s the progression of monsters that shamble out of the foul gate:

one giant toad, overgrown with fungi and weeds
a green-translucent ghast looking for fresh gnome flesh
a fey wight wearing tattered regal clothing, and a decrepit crown
a shambling mound with colorful fire flies flitting around its massive body
a young black dragon looking to make a new home in the village of Gulchbar

In addition to the monsters, each round on initiative count 20 (losing ties) the gate belches up a wave of poisonous winds. Every character must make a DC 13 Constitution saving throw or take 3 (1d6) poison damage and be poisoned until initiative count 20 of the next round.

Closing the foul gate

After the ghast comes out of the gate, let the players know that their characters realize that the gate will keep spitting out monsters unless someone does something about it. During their turn, characters can try and solve the problem (no action required). Many approaches to closing the gate are possible. You can prompt the characters to get creative and come up with their own solutions. Or, if they need some help, here are some solutions which you can suggest to the players, along with appropriate proficiencies:

Performing arcane or divine magic to deactivate the runes around the archway (Arcana or Religion)
Destroying the gate with physical force (Athletics)
Fixing the gate so it realigns to the intended position and summons healing winds from the Feywild (Arcana, Religion, Nature, or the spellcasting Ability of the PC).
Animating the gnomish master craftspeople to aid in closing or fixing the gate (Persuasion or Intimidation)

To see if a character’s attempt is successful, set a Difficulty Class between 10 and 20, have the player roll an appropriate Ability check (see examples above), and record the cumulative successes of the party in a 4-step progress clock. Simply draw a circle, divide it into four sections, and fill in one section for each successful check. After four successes, the gate is closed, Gulchbar is saved, and the encounter ends.

NPCs at the foul gate

There aren’t many NPCs the party meets in this encounter. Here are a few villagers of Gulchbar whom you can use if a character wants to interact with a villager:

Yemorn Gubbleknack. Yemorn is a cheery male gnome scout riding his axebeak mount Klat. He has golden hair and soft amber eyes. He wears a worn leather jerkin, and enjoys the open wilderness.
Fele Oakflinger: Fele is an ambitious female gnome farmer who is also the leader of Gulchbar. She is short and overweight, with messy brown hair and bright brown eyes. She wears sturdy clothing and a blue cloak.
Gatzia Silverswing. Gatzia is a haughty male gnome blacksmith. He has copper hair and sharp blue eyes, and a distinctive scar on his neck. He wears modest garments and numerous rings. Gatzia has an animal companion, a silver cat named Gaisa.

Monsters of the foul gate

You can find more groups of monsters fitting a swamp environment with this random generator!

Treasure of the foul gate

The master craftspeople of Gulchbar offer the characters a choice of magic items as a reward for saving their village. The characters can pick one of the following items.

Eyes of the Eagle (uncommon, dmg 168),
Gloves of Swimming and Climbing (uncommon, dmg 172),
+1 Weapon (any that is useful for the characters) (uncommon, dmg 213)

If the characters managed to not only close the foul gate but also realign it so that healing winds can cure the village, the gnomes also offer a small chest with

800 sp, 20 gp, a brocade merchant’s cap trimmed with fox fur (25 gp), a copper medallion inlaid with a meandros of silver (25 gp), a fine steel salt cellar set with a rosette of spinel (25 gp), a wooden coffer set with a single moonstone (25 gp)