A Scent is Key
From Destiny 1 Wiki
A Scent is Key is a hidden chest on the Dreadnaught. The chest is located in the Mausoleum of the Dreadnaught. To obtain the chest, players must pick up a scent at a specific spot then reach the chest within 60 seconds after picking up the scent. Players must go through various invisible bridges to reach the chest.
Start off in the hidden room where a chest that says "Requires Key of Maggots. Wait about 30 seconds to receive the scent. Your screen will turn green. You need to spring to the chest!! When you reach the invisible bridges you can use your Ghost to make them visible.
Take the left path. Max your agility! Use a fireteam to show where the bridges are can make this a lot easier.
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