Stain, the Hero Killer, does not possess a traditional Quirk like other characters in My Hero Academia. Instead, his abilities are purely physical. His main skill lies in his incredible combat prowess, which includes exceptional speed, agility, and swordsmanship. Stain's most notable ability is his Quirk-nullification effect, which allows him to paralyze his opponents by ingesting their blood. Once he consumes a target's blood, he can immobilize them for a short period, making them unable to move or activate their Quirks. This ability, combined with his combat skills and unwavering conviction, makes him a formidable opponent for heroes and villains alike.