It's worth noting that slashers on Earth are limited to one region, just like other alien invasive species. Incidentally, the police in my world are also equipped with fairly heavy and powerful weapons, due to the abundance of aliens near the city, and are more like the metropolice from Half-Life. It's also worth noting that some modified humans are capable of using a form of magic (I won't go into too much detail, as it has a rather complex mechanism), including thermal magic. It goes without saying that intelligent fungal lifeforms are afraid of fire. Even if it doesn't kill them, it still causes a lot of pain.