Every world has two capabilities to prevent alien invasion: the World's Veil and the Balance Rules.
Balance Rules stem from the pressure inside and outside the world. Compared to the shadow void outside the world, the unique rules and elemental forces derived from the world's Origin Will create a powerful outward pressure, repelling external invaders.
As for the World's Veil, it is a self-protection rule after chaotic creatures evolve a world, like a giant net woven from lightning, protecting the interior of the world.
Ingeniously, this protective layer of the World's Veil has great gaps between the thunderous strands.
These gaps are nothing to higher-level creatures because they are too large to slip through, but lower-level creatures can silently squeeze through them. This is the origin of the Demon Hunting Battle Merit Shadow Sorcerer.
However...
Green's world's veil physique can ignore the rule relied upon by the World Guardian as the world's strongest protective sheriff!
