Ok: I could kill someone or commit suicide, to prevent someone from killing me. Kill or be killed, right?
If you are a thing, then you "can't" do a lot of things. If you are not a thing, then you ultimately can't make someone else do some thing, or not do some thing, and if you try then it is you doing that thing. Yes? A strong worded example: God can NOT make you sin, and God can NOT make you NOT sin. Do you think I error? Do you think that is a presumptuous statement?
By saying that God can prevent someone from killing, I mean that God can quite literally do that prevention, which is not the same as making someone willfully NOT kill. When God is doing this, you can quite literally hand a mortal enemy a gun, or a knife, and there is absolutely nothing that they can do to harm you. Whereas, I could spend my entire life trying to prevent others from killing me, and will have removed from this life as a result.
The distinction is the profound difference between a man, and God. A man can kill a man, but what man can kill God, taking him away from another man? A man can kill, and afterwards do nothing more to that person. Whereas God can kill, and afterwards do more. A power above all definitions of power.
If your definition of kill is such that Jesus was never killed: similar case, different lingo.
Prayer? I do not regard pray-ing for someone else to do a thing, as doing that thing. Do you?