Siege of Darkness by R.A. Salvatore

In the third book of the Legacy of the Drow series, Drizzt and his friends managed to escape the cruel and merciless Underdark. However, in their wake, they caused a great chaos which leads Matron Baenre to believe it's time to wipe out the renegade for good. When the Time of Troubles hits, the drow armies are uncertain about their invasion. Reestablishing her dominance with consolidated power and the favor of Lloth, Matron Baenre continues to plan the attack on Mithril Hall, and in their limited time before war, Drizzt and his friends pull together an alliance to stand against the forces of Matron Baenre.