I read a fantasy book a long time agao, 14 yrs ago. But the problem is I've forgotten the name of the book.It's part of a series. It tells of a world that is divided into 3 parts; High realm. Middle realm and Low realm. The Low realm has a lot of water but that is where the poor denizens, dwarfs, e.t.c. leave The other 2 realms, Middle and High have water scarcity. The High Realms is inhabited by very powerful wizards.However, the very fabric of the high realm is falling apart, as a result, the wizards of the high realm are planning on invading and conquering the lower 2 realms. In this novel, magic is practiced by drawing runes in the air. Please if someone who has read this novel can please tell me the name of the novel, series and author, I will really appreciate it. Thanks a lot.