Thunder Dune Mountain

Thunder Dune Mountain is the 4th level of Dryrock Dunes, situated in the top parts of the dunes. This level features a large mountain that can be climbed, featuring various desert enemies. As the player climbs to the top, the weather changes to a harsh rainstorm with falling thunderstorms and rising water from the river. This level also features a certain fortress situated at the top, featuring a mission to help a mythical creature 's problem, causing all the ruckus in the process.

Level Info
Difficulty: Medium/Hard

Missions: Main Mission, Enemy Gauntlet, Boss Battle

Bosses: Thunderbird

Secret Exits: N/A

Development History:
The level started off as three separate levels made for an abandoned project called Mario and Mineroids: Black Diamond's Insurgency, before being merged together during development of Demo 3. Late in Demo 4's development, the stage received revamps mostly as a response to heavy artificial difficulty from Suckerman7's insertion of enemies and poor level design decisions made in the development of MMBDI.

Trivia

 * The music used in this level is Mor Ardain - Roaming the Wastes, from Xenoblade Chronicles 2.
 * The music used in the fortress area is Storm Fortress of Kh'lar, from the SNES game Skyblazer.
 * This level is one of the resting spots of Thunderbird, with 3 more located around the world, in desolate places like Dryrock Dunes.

Lore
Thunder Dune Mountain is the part of the mountain ranges of Dryrock Dunes, one of the largest mountains in the said ranges. The mountains are usually desolate, with the temperatures changing drastically as one climbs. This mountain is one of the nests of the mythical creature whose full name is unknown, but referred as Thunderbird. She occasionally visits this place to rest, and watch over the dunes. The inhabitants of the dunes have created a fortress to worship her, and set up a small town for people who stay there to climb the mountain and do their prayings for her to protect them.

But the mountain doesn't only have paths upwards: There are some cave entrances leading to the underground branches of the mountain, where Earth and Sand Elementals lived along with other earth/sand-borne creatures alongside them. It was the elementals' work along with Thunderbird's help that the mountains were created, for a safe-zone to protect the dunes from dark forces.

But dark times have arrived where Thunderbird has been forced to come here by sensing the presence of a dark force rising: The misuse of Star of Drought, who is now in the hands of an undead turtle pharaoh working for Bowser. This dark influence had brought her here to settle the balance, but of course, fate had other plans. After eating a bizarre thing, Thunderbird's condition started to get worse as her stomach started hurting severely, with her screams starting to rise the water level of the river and starting harsher thunderstorms that never happened in many years... As nobody dared to approach the creature to cure her, three valiant heroes decided to take up the case...