On the battlefields of Signus Prime, Sanguinius came face-to-face with the powerful Ka'Bandha, a Greater Daemon of Khorne, for the first time. The daemon taunted the Primarch, revealing Horus' planned treachery against the
Emperor. Enraged, the angelic Primarch fought the brutal Bloodthirster in single combat. Seizing the initiative during the battle, he surprised Ka'Bandha with his frenzied assault, stabbing his
Power Swordinto the daemon's chest, ripping open a gaping wound. The massive creature roared in fury and pain, lashing out with his whip at the Primarch's legs. Sanguinius was momentarily unbalanced as his legs were crushed in the whip's coils. The daemon then smashed Sanguinius to the ground with the flat of his axe. The winged hero of the Imperium was stunned, helpless before the Bloodthirster's wrath. As his vision cleared, he looked up at the monster that towered over him. The Greater Daemon taunted the Angel one final time, let out a mighty bellow and then struck out across the battlefield, slaughtering 500 Space Marines with huge swathes of his massive axe. They psychic backlash of the deaths of so many of his sons traumatised Sanguinius, and the Primarch fell into unconsciousness.
It would not be until the closing days of the Horus Heresy that Sanguinius would once again confront the savage Daemon Lord. During the
Battle of Terra, the Bloodthirster confronted the Primarch atop the Eternity Gate of the
Imperial Palace which guarded the way to the Emperor's throne room. The Greater Daemon struck Sanguinius, casting the angel upon the broken stone. Preparing to strike a killing blow, the Primarch called upon his last reserves of strength and power. With a massive effort, he confronted the Greater Daemon for the final time and leapt upon the Bloodthirster, seized him about the wrist and ankle and rose up high into the air. Sanguinius slammed the great beast across his knee, breaking the creature's back with a powerful crack. He swung the body of Ka'Bandha around and hurled the broken behemoth into the midst of the daemonic host, slamming the Eternity Gate shut against the ravening hordes of Chaos. The servants of the Ruinous Power would not claim Terra that day, and the Traitor Legions were ultimately defeated when the Emperor bested their Warmaster Horus in single combat aboard his flagship the
Vengeful Spirit.