Collapse
From UnderlightWiki
Collapse occurs when your Avatar in the Dreamstate has taken so much damage, it collapses unto itself, forming a floating sphere which is the soul of the person collapsed. This floating sphere is known as a Soulsphere. If enough damage is done to the soul sphere, it is not only possible, but likely, that the person will die. The best known way to inflict this level of damage on a person is the Dreamstrike.