The Ice Dragon (Underworlds #4‪)‬

The epic conclusion to the action-packed arc!It all comes down to this.Owen, Dana, Jon, and Sydney have to prevent Loki from finding the powerful Crystal Rune. That means they need to find it first, no matter what. But tracking down the rune is only the beginning. . . .Loki is taking his battle for power to the world of the Norse gods -- and he's bringing an army of Underworldly creatures with him, including a fierce ice dragon. The stakes are high: Dana's parents are missing, and Pinewood Bluffs is under attack. Loki is threatening to destroy our world - for good. Owen and his friends can't let that happen. But do they stand a chance of stopping him?