Frozen Apocalypse: I Level Up By Eating Snow

The world ended in ice. Temperatures hit -60°C overnight. Cities buried. Humanity's best hunters annihilated. The awakened rule now—the rest are slaves. Walfred was nobody, one of the unawakened and useless. Then came the warehouse run that should have been routine. Monsters ambushed. Walfred ran for his life as his teammates were ripped apart one by one. But when he falls into a frozen pit and desperately drinks a mysterious glowing liquid, he awakens as a hunter. With the Frost attribute. The single most worthless power in a world where every monster has cold immunity. Except his unique skill changes everything: [Unique: Frost Feast] [Gain experience by consuming ice or snow.] Hunters kill to level. He just eats. The frozen world is his infinite buffet. Become strong enough to survive, or die trying. — Description from novelcodex.org