The last stone for +10 Moonveil, there are only 8 of them in the entire game (the ability to buy infinite stones via bell bearings only applies up to +9), and they are in endgame regions (5 are in the optional hidden endgame areas!).
I was looking up potentially getting one specific stone in an area that you can try teleporting too, but then I realized it’s inside a fairly difficult dungeon.
My Moonveil was basically stuck at +7 until I hit the endgame.