Looks cool! As a suggestion, you should put the tower in a layer above the terrain that’s the ‘floor.’
In this screenshot, do you see how the edge of the sand looks different next to the grass than the marble? That’s because the marble is on the same terrain layer as the sand. Adjusting the layer of the sand would make it look more consistent.
If you need to know how to place terrain on different layers, check this guide. Hope this helps!