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Dive into the acid to the left of the first floating platform to quickly drop down the room, holding left. Use a flash suit to activate a diagonal shinespark after falling just far enough to clear the large stalactite.

Requires:

"canDash",
{"notable": "Reverse Acid Dive"},
{"obstaclesNotCleared": ["A"]},
"Gravity",
{"heatFrames": 405},
{"acidFrames": 280},
{"useFlashSuit": {}},
{"shinespark": {"frames": 38, "excessFrames": 0}}

Unlocks doors:

{"types": ["super"], "requires": []},
{"types": ["missiles", "powerbomb"], "requires": ["never"]}