Kol Raiders are essentially just Raiders, but they have a nasty habit of setting themselves on fire when they die. This fire deals damage if you're within the radius, but you can avoid it entirely by killing the Kol Raider with a stun finisher.
Raiders will almost always come at your swinging, but that makes them easy to predict. They're standard humanoid enemies, so a couple of good parries should be enough to stun them completely, and leave them open for a finisher.
While their aggression does make them easy to read, as mentioned, you still have to be careful when fighting multiple Raiders at once. They'll come running at you from any and every angle, so try not to get surrounded.
How many Kol Raiders have you smashed into submission? Be sure to check out our full God of War Ragnarok guide for information on how to beat every enemy, and much more.