The Imperium has be brought to the edge of extinction by an ork invasion of unprecedented scale and depth. Piecemeal strikes against the invaders prove ineffective - for every ork fleet destroyed, five more appear. The only solution is to find and kill the orks' warlord - the Great Beast. Surely if its leader is killed, the greenskins' empire will fall apart in agony of infighting and confusion. Lord Commander Koorland assembles a mighty army, but when they arrives on the orks home world, the forces of the Imperium discover they have disastrously underestimated the might and ingenuity of their enemy.
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A primarch, the last Imperial Fist and the biggest Imperial army since the Heresy walk into the ork homeworld… but it's no joke. This is the big one, and drama is guaranteed.