There is a third tier to ammo for the trebs. That is stone bolders and iron bolders. Then there is the mini nuke, 3 bombs tied. If that is not enough, then I recommend using a god, whos fun lasts longer.
I agree, but this last patch seems to have fixed a few issues. Top one being npc spawning in dungeons and caves. I mean the npcs do not spawn under certain conditions. Not fun if your base caused it. 