Keter, pronounced ket-er, is usually the most dangerous type of anomaly that the foundation contains. "Contains", in this case, is a very genorous word. Essentially, keter class SCPs have containment breaches on almost a weakly basis. Now, I know I said that the worse the classification of the anomaly does not mean the more dangerous, but, as far as I know, there are no keter class SCPs that will not kill you if given the chance. Essentially, just don't end up in those situations in the first place and you will be fine. You seriously have no chance of surviving an encounter with SCP-682, a large reptilian creature with a thirst for the destruction of mankind, which, fun fact, also adapts to ANYTHING. It's even hypothesized he could evolve to shrug off an entire nuke, which is why the foundation hasn't tried that to kill him. Know, for those who know that it's the GOC, Global Occult Collolition, who kills anomolies, SCP-682 is the one SCP that the foundation has tried and is trying to kill, as it is very hostile and immune to almost anything, even a knife that when you cut something with it, is removed from this and EVERY timeline where it ever existed. It worked for a second, but then he just came right back and instead it was the knife that disappeared. Sorry about my rambling. In summery, just don't end up at the wrong place at the wrong time.