Mortally wounded
Leaving aside the mana that was what allowed even non-living things to grow by the mere fact of existing, the universe was mostly made up of Dark Matter; one of the main reasons why even the powerful radiance of the brightest stars could only illuminate an extremely pitiful amount of the vast universe even though there were countless of them hanging in the sky.
With Darkness Manipulation in his hands and being his main skill, Lucifer was one of the most powerful Leaders. At the end of the day, the universe was a wolf's den where the darkness was as deep as the disappointment of a person in love and illusion for something that never existed.
In fact, Long Tian knew somewhere deep in his heart that if he fought Lucifer in a 1 vs. 1 battle outside the atmosphere of a planet his chances of victory would immediately plummet.