Geographical locations that act as natural magic wells), as a strong source of energy is required to activate the Grail. Further capturing them and binding them to you grants your servant better abilities, as you are now counted as being one master rank above what you actually are.
Say a level 4 (D) master captures a leyline and feeds of it, His servants stats change to a C for as long as the master holds the Leyline.
Holding a LeylineEdit
Holding a Leyline is easy, all you need to do is hang around it. preferebly set up your base at it, while you can just pass through it or hang around awhile, unless you cast a 12 hour ritual you cannot "capture" a leyline. However even if you just hang around a Leyline your servants ranks will go up a whole rank. But only for as long as you are around it. If someone else casts a capture ritual the ownership is transfered to the person who cast the ritual the latest.
Ownership is noted in a sticky on the forum.