During the «Showdown! The Gloomy Cavern» quest step for the Carnival of Fireworks main questline in , you'll be tasked with opening a mysterious sealed door that leads to an even more mysterious cave.This cavern is found on the north side of the Firework Isle. You'll be led there by Marques Jr. after receiving the mysterious sword from the stone, but you won't be able to get inside until you find all three Launch Tubes that keep it sealed.
These Launch Tubes, like the ones used to seal the doors in the other three caverns of the Firework Isle, are «hidden» across the island. They're less hidden and more tucked away, but the map beside the door isn't especially precise, so you'll have to do some hunting to find them all. Many of them are found among or near groups of Esselings, so remember to be on your guard as you explore. If the Launch Tube hunt doesn't tickle your puzzle-solving fancy, check out the New Bloom Festival's Whim Tangram puzzles, which take both logic and patience to solve.
Once you reach the "" part of the Carnival of Fireworks main event quest, you'll get a waypoint marked on your map that takes you to a Warp Spire just outside the Gloomy Cavern. There are a few Esselings nearby, but they're easy enough to take care of for any player who's gotten this far into the game. Once you approach the cave, a tooltip will pop up telling you to check out the stone map next to the cavern's entrance. This map shows the approximate locations of the three Launch Tubes needed to open the cavern's door.
To light the Launch Tubes, you'll need Firey Glow, which is a Fireworks Ability Outfit added to the roster of outfits that arrived in 1.2.
The first Launch Tube should be obvious. It's in front of the cavern door, near the Warp Spire, on a small stone platform. Light it by using any Firework Ability Outfit, after which it will shoot off a pink firework, which will trail toward the cavern entrance and cause one of the gems in the door to light up. The next two Launch
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