The We Need to Go Deeper description is misleading. It tells the player that they have to ''Build, light and enter a Nether Portal'', when in reality all you have to do is enter a Nether Portal for this advancement to trigger. Someone else could have built the portal and it would still count.

Compare this to the ''The End?'' advancement, which simply says ''Enter the End Portal''. This description is accurate, and it would make sense to change the ''We Need to Go Deeper'' description to something along those lines. It would make it more accurate and also consistent with the advancement for The End.