“I was a strong effort in the spirit of good; but it was ineffectual. Destiny was too potent, and her immutable laws had decreed my utter and terrible

This statement is an extreme instance of foreshadowing by Shelley - almost overkill in fact. While it adds suspense in a way, as the reader knows that something tragic is to come, but doesn’t know exactly what, it also takes away from this suspense. There is no question in the reader’s mind that all is doomed for the protagonist and the only question remaining is exactly what will cause this downfall; the reader knows from the start of the story that Victor will not survive to experience its end.