How does Moonbeam work? [duplicate]

So, I saw a similar question explaining that Moonbeam and other similar hazard spells don’t deal damage when they attack. However, since moonbeam is able to be moved, are the enemies considered ‘entering’ the spells AOE when it moves on to the tile they are standing on (if it comes to rest there)? The other answers and the wording lead me to believe that it could go either way, so I am curious to get some of your opinions.