The gods warn that the orcs indeed have the blessing of Gruumsh for this invasion. They are lead in worship by an aged, veteran orc, Gruuman Xuluksh.
This orc has been feeding his god with the blood of vanquished foes for too long. As Gruumsh gluts himself on ill-gotten spoils, he grows bold and threatens the balance of the cosmos. the benevolent gods will no longer tolerate this.
To slay an enemy is a macabre act, but when it must be done, let it be done swiftly and without remorse. Kill Gruuman Xuluksh and end this divine travesty.