From Fear. Princes of the Blood, #4

Fifteen years ago, several wolf pups were kidnapped by poachers to be illegally sold abroad. They were rescued by a Prince of the Blood, and the Wolves of the Moon vowed the debt would someday be repaid. Now of age, wolf Ilkay Thrace is determined to fulfill that vow. Before he can, though, the Wolves' home high in the peaks of Dragon Claw Mountain is ravaged by an earthquake that reveals an ancient, forgotten temple-and awakens something dark and terrible in its depths.
Now, instead of repaying their debt, the Wolves must once again ask the King's Legion for help. Despite the time that has passed since the Legion was nearly wiped out, their greatest strength, the Princes of the Blood remain few. It is one of their newest, Prince Dalibor, who is sent to evaluate and assist the Wolves. But Dalibor is born of a demon of wrath, his greatest power the ability to drive all living beings out of their minds with rage and fear.
He is brash, loud, and reckless, even by the standards of the Legion, and the very last person that should be going into dark, treacherous caves containing ancient evil.