This is only in CERTAIN situations. It is not illegal if it is a random TP and you accept it. YOU are taking that risk when you do so. So, do not accept the TP just to report them, it will be invalid. It is illegal when they offer you something. Like how Ninja said, it is considered scamming. If they offer you, let's say a TP to a base. You accept the TP and you get 5v1ed. That is illegal. If they offer you any item, area, etc. It is very specific, just watch out for YOUR actions. It could cause you to lost items or something you value. People always ask us to refund their scams. We cannot do so, we do NOT have access to Creative. YOU are responsible for the risk your making when doing so. We will try our best to refund with OUR values, but if we cannot refund entirely, we are sorry. Hope this cleared things up for you!
Like @Grayson said above, if it involves you giving them items or money before they kill you, then it's classified as scamming.