Warhammer The Horus Heresy: Legions Shadow of the Warmaster expansion is being fully revealed at a later date and will bring over 200 new cards and many new features and improvements, including a battle pass. The Shadow of the Warmaster expansion gives both new and existing players two complete starter decks, one from the treacherous Sons of Horus and another from the loyal Imperial Fists making it the perfect time to enter the battle.