The smallest brush is 1\8 mile dia. I pulled small hills with the raise hill tool set to 1ft\sec and I believe what gets raised is the center cross points of each polygon crossing point. You can watch this by turning on "Wire Frame" as you pull hills. If you place the brush center of two groups adjacent to each other, you also raise the space in between. The closest you can get and have individual tiny hills is every other polygon intersection. So you are limited to small hills about every 1\4 mile. The berms on terrain editor standard objects like in the town and the tank town object are custom objects created by Waffle which have been standardized to those objects.
Part of why in the tank combat caldera on my terrain I put those 500ft galleries above the Pit. The whole area in the original iteration sloped like a bowl to the center and I tried to create berm like areas up in the gallery. You could try a 1\8 mile dia brush and the alt tool set to just bump a low cylinder up 25-50ft above ground level. That is not much different than using the raise hill set to 1 ft\sec. In the end the real test is to spawn next to one of these in a GV and look at them. They end up being clunky but, if they are for long range sniping, throw a few trees on top hopefully getting some near the edge if you do a cylinder, and smooth an access ramp. If they are for playing peeka boo in tanks, they suck because the edge of the nearest cylinder has to be 1\8 mile away. Or a hill edge that far away for the "V" in between two hills. But, the taller you raise the two hills to deepen the "V", it starts raising up also creating a two tit sharp saddle back between the hill centers.
So for peeka-boo, it starts making sense the clutter tiles Waffle gave us, especially with the village tiles. Unless lunatic can convince Waffle AH3 will become a ghost town if he doesn't cut loose with some berm themed clutter tiles "ASAP". Lunatic already threw out berms at me months ago, so I tested the feasibility in the farmland down in the tank crater Pit on my terrain during the final tweaking process.
I think the AvA guys have custom berm tiles but, custom objects and tiles are allowed in the AvA, versus the MA in which all objects and clutter tiles have to be standardized so some minority of players don't get hit with strange random issues. Maybe Waffle could create say a dozen boulders from 10ft dia up to 40ftdia that can be laid down in limited groups. Still, some joker would try to build a maze or something that he would know all the sweet spots in for months to win tank fights. Yet things like this are in the AvA for lunatic if he really wants them.