Setting: a room in the school of magic. Seated at a desk infront of younger students is Rusvanus as meticulously groomed as ever. He answers questions any of the students may have and occasionally wriites something down in a book
Rusvanus: You see class, mana is colective substance. it is all around us but it is part of us as well, so it is not infinite. there have been times I have come too close to using all of my mana and it has left me quite weak and vulnurable. Apparently SOME of you think you can cast your spells all day and expect no ill side effects. *glances at a young male in the front row, who ducks his head in shame* No matter. If you do not learn by the help i offer you will have to learn from experience. Now i know you have your lessons to attend, so if you have a question, ask, if not do your work in silence.
*with that he opens the book agian and begins to write, every now and then stopping to keep an eye on the students and to stop any carousing before it began or got out of hand*