They burned their books.
There is a lot going on in this portion of scripture. We see the son’s of Sceva getting their butts kicked when they try to act in Christ name without having relationship with the Christ himself. We also see in verses 19-20 real signs of repentance. This is where they burn their expensive magic books. This is where we are given an example of showing “fruits” of repentance. This raises a question each and every one of us needs to deal with at one point in our life or another. What is it that the enemy has used to ensnare us that we haven’t walked away from? Repentance is exactly that. Repentance is walking away from those chains that the Christ through his death and resurrection has freed us from. We have a choice. We can walk away from those chains, or we can pick them up, put them back on, and put the paddle lock back on them. These folks burned the books. When they did that the chains were destroyed. Just remember this. When the Christ through the Father by the Spirit sets us free we are free. Do not put those chains back on, walk away from them. Be free.
Go in peace