Good thing nobody else seems to be able to figure out how to approach it.
The anti-hog ring is setup so that even if they breach the core, they are going to be sucked back into the ring. And even if you trigger the obvious giant bombs, there are 6 spring traps that will take up to 18 hogs out of the battle. And while the hogs are hopping around the ring, they will be harassed by the BK in addition to skeleton traps. As you can see in the screen shot, my base was gutted but the TH is still standing.