Runemaster — Macaulay C. Hunter

Skorungur is at war. Rafe Swale is caught in the crossfire, the search for her mother brought to a sudden halt. Sent underground, she learns of a mage game in which winners are gifted with knowledge from the gods-of-runes. This may be the only chance Rafe has to find out what happened to Paige Swale. But this is no ordinary contest; mage game demands blood as tribute. As the Gatecrashers and their friends move from one dangerous level to another, losing members to injury, despair, and death, Rafe wonders just how high the price will be.