"The Abyss Demons' Attacks" 

"Low-level demons need at least an hour to completely recover from serious injuries while mid-level demons only need thirty minutes." 

This was why, abyss demons were difficult to be wiped out, and the ancestors chose to seal them inside a brand new dimension. 

"Abyss demons only die if they were purified, attacked with light element abilities, or devoured by fellow abyss demons and other creatures that feed on miasma." 

Unfortunately, such special creatures didn't live in the four seasons island, not to mention the snowy mountain range. 

"Our strategy will be to ask all light element ability users and those who can use purifying ability to deal with the demons while the others will have to freeze the demons so that they can't recover." 

Then, all they could do was to wait for light element ability users and purifying ability users to kill the trapped demons. 

The old general shared this tactic with all contestants and the students.