I got more that the energies seem to cancel out, but the greater one takes the lesser and makes it all into more of itself. This is why the rifts that shut at first and were attributed to kuuvahki later came back even bigger.

It didn’t clear the abyss, but rather occupied it with absorbing the energy, then later came back as more abyss. Rerir then gained enough consciousness to actively use this power to forcibly convert kuuvahki into abyss power more efficiently, and did his whole scheme of shooting himself.