 So you just want to boolean subtract two objects together, not a problem. If you have two objects that you want to add together, just use the dynamesh method like I said before. But if you have a cool shape and you want to subtract another object from it, get whatever shape you want, turn live boolean on, and change it to subtract mode. And now you can see that the second object will literally carve into the first however you want. If you change it from subtract to intersect mode, instead only the intersected areas will be visible. But we're going to subtract, so for now I'm just going to set it like this. Now you can have more than one object subtract at the same time, which is super useful if you want to carve out hard surface details or specific shapes. Now let's say that you like this specific shape and you would like to finalize it. Well to do that, under boolean hit make boolean mesh, and it should appear up here. And now you can append it to your subtool like so. At this point just use your standard polygroup and z-re-mesh to automatically fix the topology and bam, you're done. Well that helps and as always hope you have a fantastic day and I'll see you around.