Avatar of Suffering

All creatures except Avatar of Suffering get -7/-7.
Whenever you gain life, opponents lose life equal
to the total life you've gained.
No suffering is self-caused. Nothing causes itself.
If another is not self-made, how could suffering
be caused by another? If suffering were caused by
each, suffering could be caused by both. Not caused by
self or by others, how could suffering be uncaused?