Or more properly:
He had the intent to do far greater damage.
or
He was intending to do far greater damage.
The quality or amount of his intent is not the subject. The actual intentions is the subject.
Sorry. It’s early morning and the quote instantly bothered me. You have to admit that it is an unusual sentence. :)
Bother me too. “His intention was to due far greater damage’’ or “His intention was to commit murder’’.