The plunderer ability that Alex had was an ability broken to its core—that is what anyone would say if they knew about it.
And it actually was just that, as it gave Alex one thing of his choosing from his enemy if he is able to defeat them and everything that the enemy has if he kills them.
So, right now, when he stared at Lokiath, who was anxiously trying to break free from here, Alex knew that it wouldn't be long before the guy had found a way to vanish from his sight.
Alex wanted to stop that, and to do that, he had to either kill him or take away his golden finger.
The golden finger is the only thing that Lokiath can depend on, as it is a system, so Alex decides to play a game with the guy.
Why a game?
Because Alex needed to defeat the guy for his plunderer ability to work, which he had yet to do.
Even the moment he knocked Lokiath out on his bed, it wasn't a defeat, as it was never a match; it was just an attack.
