"Elite Valkyries vs Island Devourer" 

Although the Island Devourer was a normal creature in the third level of Hell and many other Hell Creatures were stronger than them...

There were reasons why the Island Devourer could become the one who came out of Code-L's Hell Crack. 

It was common knowledge throughout the third level of Hell that to be able to use the Hell Crack opened by otherworldly people leading to other dimensions or worlds...

The Hell Creatures would either be lucky or strong enough to defeat all their rivals as soon as Hell's crack opened. 

Although the Island Devourer couldn't come out of Hell and could only stick out its tongue because of the crack's size...

How could this Island Devourer be able to occupy this Hell Crack if it didn't have a few tricks on its own? 

Many Hell creatures had evolved continuously in a harsh environment, so even the most ordinary creature that could be seen everywhere in the third level of Hell had special tricks on their own.