The Oasis Descent

Beneath the oasis, buried magic fails one silver ward at a time.

7 roomsThis is the under dungeon located on the basement of an old abandoned mage tower in Netheril. The tower is now in de desert of Anauroch in one oasismedium

Beneath an abandoned Netherese mage tower, a cracked stairwell descends into an old maintenance entrance built from black stone and silver inlays. Flash floods from the oasis have invaded the lower halls, filling channels with shallow water and loosening the sand around ancient wards. A sealed bronze door marks the boundary between this neglected threshold and the deeper chambers where a magical catastrophe was contained.

The air is cool, wet, and mineral-rich beneath the desert heat. Thin sheets of water gleam across black stone channels while failing silver wards emit a faint violet shimmer, accompanied by distant drips, settling sand, and occasional groans from the tower above.

☠ Threat

The deepest chamber holds the Echo of Vael Turog, a fragment of a Netherese archmage fused with the damaged water engine. It cannot leave the sealed complex, but it can animate maintenance constructs, distort the failing wards, and draw more oasis water into the dungeon. The Echo seeks living minds to repair the engine and restore the tower's lost connection to the Weave.

History

The under-dungeon was built by Netherese surveyors beneath a mage tower that monitored the oasis and controlled a buried reservoir of enchanted water. Its maintenance halls housed pumps, ward relays, and emergency seals rather than riches. When the tower's master attempted to draw power from a falling star, the reservoir ruptured and the lower complex was sealed. Centuries of sand, floodwater, and failing magic have begun reopening it.

Encounter Table

CR
1/2CR
Ward-Eating Scavengerx1d4

A pale, many-legged scavenger covered in wet sand and tiny silver fragments. It feeds on crystal relays and flees from bright flame.

1CR
Rogue Maintenance Shellx1

A damaged stone construct carrying a rusted maintenance hook. It mistakes explorers for repair crews until they approach a sealed mechanism.

1/4CR
Silverglass Beetle Swarmx1 swarm

A swarm of translucent desert beetles that glitters with stray Netherese energy. Their bites numb flesh and make silver jewelry vibrate.

2CR
Sandbound Water Wispx1

A half-formed water elemental with black sand suspended in its body. It cannot remain far from the dungeon's channels and attacks anything carrying active magic.

Rumours & Whispers

1

The oasis water has begun bubbling at night, and violet lights shine beneath the abandoned tower.

2

Old travelers say the tower's cellar contains a bronze door that no blade can scratch.

3

A scholar claims Netherese mages built machines beneath the oasis to make desert water flow uphill.

4

People who sleep near the tower hear a voice counting backward from seven beneath the sand.

5

A caravan guard swears that stone soldiers patrol the cellar whenever the spring floods.

Quest Hooks

1
The Bitter SpringInvestigation

Quest giver: Nalia Voss, the oasis settlement's practical water keeper

A caravan route depends on the oasis, but its water has turned bitter and warm. The characters are asked to investigate the abandoned tower before the settlement loses its only reliable source.

A selection of desert supplies, 150 gp, and permanent access to the oasis's hidden cistern

2
The Last SurveyArtifact Hunt

Quest giver: Archivist Meredin Thule of a distant arcanist college

A scholar believes the tower contains a surviving Netherese control sigil. Recovering it could prove that a legendary mage's final experiment was not entirely lost.

A rare spell scroll, 250 gp, and formal scholarly patronage

3
Lights Under the SandContainment

Quest giver: Seref, a scarred caravan scout who saw the lights during a night watch

Strange violet lights have appeared beneath the tower, followed by tremors and brief floods in the oasis. The characters must reach the bronze door and determine what is trying to get out.

A Netherese ward token that grants advantage on one save against magical traps, plus 200 gp

4
The Bronze SealRescue

Quest giver: Ilyra Dane, the expedition's anxious sponsor

A rival expedition entered the cellar and never returned. Their leader's journal, found in the oasis, mentions a sealed door and a voice speaking through the water.

The expedition's recovered equipment, 300 gp, and one uncommon magic item from the lost group

Corridor Notes

Between Room 2 and Room 3

Shallow floodwater runs through narrow silver-lined channels cut into the floor. The water is warm near active sigils and cold near collapsed passages.

The walls of Room 3

Faded Netherese warning glyphs repeat along the walls, showing a tower struck by falling stars and a lower chamber sealed beneath it.

Between Room 4 and Room 5

Several ceiling stones have shifted, exposing packed sand and roots from the oasis above. Loud impacts or thunderous magic may trigger a minor collapse.

The eastern wall of Room 6

A narrow observation slit overlooks the approach to the bronze door. The slit provides cover and a clear line of sight from Room 6 into Room 5.

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