He hadn't expected Leon to use such an underhanded technique such as blasting him from the inside.
If it was just a normal explosion, then he wouldn't be wounded to this degree, as his regeneration would have long kicked in.
However, no matter how powerful a person was in this life, their inner organs would always be weak and vulnerable.
Since the dragon wisp detonated inside his body, his celestial core along with a large majority of his organs were burnt to a complete crisp.
Before the wisp exploded, he managed to quickly coat some of his vital organs in mana, but even that didn't do him much good.
Leon's energy was just too powerful! It easily overpowered his mana, rendering the protective covering useless.
Nonetheless, that little action of his still managed to preserve his life, as his heart and a few other of his organs weren't completely obliterated by the blast.
