Though this voice seemed powerful, it wasn't as if just the voice alone would do anything.
The only thing that it did was catch us off guard temporarily.
But in the end, the Death Knight was still taken care of and collapsed into a pile of dust and bones.
After that first roar, the voice seemed to have disappeared.
However, when the Death Knight collapsed, the voice once again said, "How dare you destroy my Death Knight? Not only that, you destroyed the magic array that I've set up to turn it into a Dullahan! I will never forgive you!"
Dullahan?
So it turned out that this was the reason why the lich had set up that magic array in the first place.
It turned out that it wanted to gather the natural dark energy inside of this dungeon to amplify the power of the Death Knight, allowing it to evolve into a Dullahan.
