Then don't be shocked if it's harder than it should be.
The "bomb" is given for a reason.
Anyways, re-tried on Nightmare, and had to re-do once (because I died, not paying attention, lol, not because of the zep). Sure, was only 75% health instead of 90, but still nowhere near difficult to keep the zep alive. Just myself.
And fortunately kept my weaponry in the endfight this time. Not sure if that was because of Bellegar, because I put 2 other weapons in my slots "just in case" or because it was a random fluke last game...