1. Speak with Laniakea and it will get you two talking about the doorway at the top of the ruins and presence of the shadow anima pools nearby (option 2). She will tell you that things have been changing around the ruins and that a mysterious figure has been seen in the area. Suggest opening the door (option 3) and she will agree, adding that the ruins cannot be damaged in the process. According to Charos, the door can be unlocked with an infusion of the same energy that Kerapac's device was generating to unlock - unfortunately, you destroyed that device. Luckily, you still have a plan.
   
   
   
   
2. Go up the stairs to the West of Laniakea and siphon the shadow anima from the pools 5 times; note that siphoning a pool will make it so you cannot siphon from it again until after you have siphoned from another one. As such, it is suggested to stand between the 2 Southern pools and alternate which one you siphon. Each time you siphon a pool, it will deal 200 damage (1,000 damage total). After the 5th pool has been siphoned, it will bring you to a 100% shadow anima capacity.
   
   
   
   
3. Walk down the Western stairs to reach a door. Touch it and it will unlock. Enter the door and Laniakea will follow you until it becomes too much for her to do so.
   
   
   
   
4. Talk to Zaros, found just East of the door. This will begin a skipable cutscene followed by more dialogue with him and a second cutscene. Once the second cutscene completes, you will have a short conversation with The Keeper before you are done.
   
   
   
   

Congratulations, Miniquest complete!