Lind's meridians were on fire. His organs were damaged and his dantian was just barely stable. He had done a very foolish thing but he had no choice.
He had tested and proven he could handle demonic Qi for a short time. He could Forge, make elixirs, or even engrave with demonic Qi. It strained his dantian and meridians but not in a way that was beyond any issue he could fix.
The worst he ever suffered was having to take over a month off of cultivation to purify his body entirely of demonic Qi. It was simply that his body could not withstand the savage nature of demonic Qi for very long.
He had only once tried to use Celestial Qi since he understood it was some variation of Fiend Qi but not vile at all. The single time he had used it had nearly burst the meridians in his hand.
