His actions weakened him to a terrible extent. After all, from an entity that was empowered by all the deaths in the multiverse to someone now only empowered by the deaths in his Dreamland, Compass Carburettor's strength fell by a lot.
It had to be understood that his concept was Mortality. Meaning, his concept only existed at the moment of a life's death. So, at that moment, it empowered him.
But before and after that, he wasn't empowered.
Meaning, if suppose ten million creatures were to die at one moment, Compass Carburettor would be empowered accordingly. But in the next moment, eight million creatures were to die, it would mean a reduction in his strength by twenty percent.
This was how concepts functioned. If they were in use, they functioned. If not in use, they vanished. The greater their use, the stronger they were.
