Luminescent Seeds are planted in the chest-high Hands that dot the three main Patrol areas of the Pale Heart. If you have a Seed and there is a nearby Hand in which it can be planted, the Hand will be highlighted with a diamond shaped waypoint. You can increase the distance at which such a waypoint becomes visible by equipping a Sniper with a high Zoom stat and ADSing. By running a full lap and then criss-crossing each map while occasionally ADSing you should be able to locate all the Hands without too much difficulty. Once every Hand within the Pale Heart has had a Seed planted within, you will no longer gain additional Seeds from completing Overthrow Boss fights. Unfortunately if you have any Seeds left over at this point they will not automatically delete themselves, leaving you unable to rid yourself of them; a means to dismantle Seeds in your Inventory or a flag that automatically deletes all Seeds once the game recognizes that all Hands have flowered absolutely needs to be added. (΄◉◞౪◟◉｀)