You can only ever get one seed of light from Blind Well. After that, you can get another from: - Visiting Mara's Throne Room and opening the chest during high curse week (that's this week) - Finishing the first encounter of the Last Wish raid. To visit Mara's Throne Room you need to pick up the Gateway Between Worlds bounty from Petra (if you have an incomplete one in your inventory, discard it and pick it up again). Complete the necessary amount of Blind Well to complete the bounty. This will give you an Offering to the Oracle. Take that to the Spire of Keres and offer it to the Oracle Engine. It will open, allowing you to enter Mara's Throne Room. The chest will be on the right side of her Throne.