ring breaks ghoul back

I raised my staff in my fist, baring the rings to the ghoul, and as I triggered the first ring snarled, "See ya!"
Raw force lashed out at the ghoul, flung him off the end of the Water Beetle, and slammed him against the front of the ship blocking us in with enough force to break his back. There was a rippling crack, the ghoul's battle cry turned into an agonized scream, and he vanished into the cold waters of Lake Michigan.
The first of his buddies was already in the air, boarding the Water Beetle just as the first had. I waited a half second, timing the arc of his jump, and before his feet touched down, I hit him just as I had the first one. This time, the ghoul flew back into a pair of its buddies, already in the air behind him, and dropped all three of them into the drink. Ghouls five and six were female, about which I did not care in the least, and I swatted them into the lake with two more blasts.
So far, so good, but then four of them all leaped together - probably by chance, rather than design - and I knocked down only two of them. The other two hit the deck of the Water Beetle and flung themselves at me, claws extended.

White Night Chapter 21, Page 199