The Crystal Shard: The Icewind Dale Trilogy, Part 1 (Forgotten Realms: The Legend of Drizzt, Book IV) (Bk. 4)
This was the first novel written and continues where Soujourn end. The meeting between the three friends with the barbarian Wulfgar. The forging of Aegis-fang and the first battle against Crenshinibon (a crystal shard) a magical sentient possessed by Kessel a wirzard and we also learn about Ertuu a balor.