I Only Guarded the Empress, but Became the Strongest in Murim

When Yoon Seo awakens in a martial world shattered by war, he finds himself serving as the bodyguard of a peerlessly beautiful empress. Worse still, a deadly poison is spreading through his body, and the only way to survive is an intimate yin-yang harmony with her. After escaping death, the poison vanishes—but in its place, an incomprehensible power takes root within him, and a battle card system activates.