One of the most dangerous enemies can be found in Persona 5 Royal's Metaverse, known as the Reaper. Unlike the regular enemies you encounter, the Reaper is extremely difficult to beat and tends to show up if you spend too much time in Mementos. In fact, Morgana keeps suggesting that Joker should avoid the Reaper at any cost since the boss can one-shot party members quite easily. Therefore, it is recommended to battle the Reaper once you've acquired or fused powerful Personas.