read the passage.

[the] witching hour had gone by. … i did not sleep. … my imagination … guided me, gifting the successive images … with vividness far beyond the usual bounds of reverie. … i saw the pale student of unhallowed arts kneeling beside the thing he had put together. i saw the hideous phantasm … on the working of some powerful engine, show signs of life and stir …
which words in the excerpt from mary shelley’s introduction to frankenstein create a dark mood?

vividness far beyond the usual; my imagination; bounds of reverie
some powerful engine; kneeling beside the thing he had put together
i did not sleep; gifting the successive images; show signs of life
witching hour; pale student of unhallowed arts; hideous phantasm