Even if they don't gain any power, devouring the void universe will surely expand their existence, which will buy them more time from ANNIHILATION and also provide energy for them to use the aspect of Time to speed up their evolution.
These are things that they desperately need to resist ANNIHILATION. So they didn't hesitate to devour everything.
They unleashed the abyss within them, which caused a giant whirlpool that was devouring everything to appear in the void universe.
They also used their immense power to affect the space of the void universe and pull everything within the universe to themselves.
While they were doing this, ANNIHILATION was also destroying them. Other powerful beings were also trying to escape the void universe.
