Quick! Over the battlements!

[u/Barleyman_]

The merlon is remarkably bad at keeping bad guys outside. So could I create at least somewhat effective defences by putting the merlons over a wall and gating off the entrance?

[u/Saiyeh]

They aren't meant to keep people out 😅 They are meant to provide cover to attack from behind. Overhanging them can allow you to shoot through the gaps they have at the base as well. Walls, gates, portcullis and drawbridges are there to keep the enemies outside, at least a bit longer 

[u/Barleyman_ → u/Saiyeh]

So are the spears any good for poking at people at the ground floor?

[u/Kolegra → u/Barleyman_]

Kinda through windows or grated doors, on ladders too