So first off, it’s not a typo, this group is actually called the collision. Yes, like things hitting each other. Because hitting stuff is exactly what members of the collision do. 

the collision is a melee centric gang of bruisers. They love finding excuses to rob and hit things. With this common goal, the collision seeks to take over the other groups in the land to establish a empire where they can indulge their barbaric ways. 

anybody who stands in the way of the collision, gets treated to the name via homemade or industrial bludgeons and wedges.  Always looking for something to hit, being labeled as an enemy is easy

oppose their beliefs: you get a smacking 

fight: gladly 

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live in their territory without permission: talk to the shovel 

stare at them for too long: “oi I think this one wanna foight”

be smart and use ranged weapons: heresy 

so on: so forth

the reason why the Collision hasn’t been taken out by a redneck with an ar15 is from sheer numbers and influence. Using swarm methods, and a you can’t stop all of us mentality, collision members can easily overwhelm most. 

but the real reason why they are so prominent is their leader. As stashed in checkpoint some people who survived the happenings (weird magic waves) got power beyond science. The leader is one of those fellows who got such powers. 

it seems the powers given are specific to the user, as the leader’s power is to be completely immune to any flying objects, only harmable by melee attacks. Which bad because he’s an ex-boxing champion, known to be a nightmare in hand to hand combat. 

tl:dr 

The collision, yes that’s spelled right, are basically raiders with ork mentality about combat and a explicit use of melee weapons. It’s easy to get on their bad side, and wish to conquer.