Normally when you claim some runes from the mage tutor and come back she says;
"You have some mind runes in your (inventory/bank), why not use them"
So heres how to do this - first go and claim runes then wait a half hour. next go RIGHT outside the place and drop them or else she'll say"Someone has droped some runes on the floor, why not use them".So then talk to her and you get More Runes! Pick up and keep repeating the procedure until you're satified.

~Happy Gaming~
From Pichu-vids!