The Hunt - David Annandale

The world of Tallarn knows no peace in death. Loyal Imperial forces rise up in defiance of the Iron Warriors Legion, and the poisoned earth shakes beneath the treads of countless battle tanks and war machines. The traitor primarch Perturabo appears to be on borrowed time, with emissaries of the Warmaster and other, less visible agencies following his every move as the apparently senseless battle continues. But there is a reason for his stubborn commitment - a secret that has lain buried beneath the surface of Tallarn for millennia...
Read it because
A legend returns to the Imperium in its hour of need. if Koorland and his warriors can fight their way through an army of orks to reach him, that is.