How do I learn assassin moves?

So I want to be skilled like an assassin. I know it takes years. I don’t actually want to hurt people I just like how alert they are of their surroundings and able to defend themselves against more than 2 people at once and know the dangers of explosives and guns and other things and can know when there’s a trap they’re going to walk into etc. what lessons can I take to learn skills like this? Karate? Kickboxing? I have no idea.
How do I learn assassin moves?
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