Liches had escaped death, but that did not mean they could not be destroyed. They too had weaknesses, and various powerful mysterious forces could tear apart a Lich's soul. Holy Light could do it, as could the void where shadows dwell.
When that ray of light appeared, all the spectating Liches were surprised. And when the Flying Shuttle, obviously carrying Mr. Delusion, charged into the black hole, the Liches had already become so astonished they were nearly in a trance. For that moment, even the Soul Fire ceased its flickering, their active minds seemed to freeze, thoughts turned into rusted machinery, rigidly contemplating the reason, attempting to explain everything before them.
Why was he so brave? Had he truly gone mad? Or did he think he had no way out, and in a fit of desperation planned to commit himself to a martyr's death?!
In the view of the Liches, Delusion's actions were foolish yet brave.
Foolish because they would not do such a thing.