Apocalypse: My SSS Ability Changes Every Few Days

Alex woke up one day to find that the Apocalypse had begun. Chaos ensued as animals that were usually harmless went rabid. Some of the students in his college were attacked and killed by them. That was when he realized that things weren't going to be the same anymore. He had to figure out a way to survive in it. Fortunately, Alex awakened a system that granted him a new ability every few days. He could keep each ability as long as he fulfilled a condition set by the system. He went on to establish himself alongside his friends and allies, striving to become the strongest in this new world.