The Hero King stole the Celestial King's Celestial Jade, giving it to the Infernal King, and then he stole the Infernal King's Infernal Sword, giving it to Leonis. After that, he pretended to be a Celestial and destroyed half of the Transcendence Holy Tree, causing the Celestials to hate the Infernals, the Infernals to hate the Transcendents, and the Transcendents to hate the Celestials. It instigated the first three-realm war in history!
It was not an easy task to do the three things simultaneously. The Celestial Jade and the Infernal Sword were the most precious treasures of the Celestial King and Infernal King respectively, so it was obvious how high the security around the two items was. It was not easy at all to steal them from their respective kings' hands.