accursedly

In an accursed manner.

And now, when Danforth and I saw the freshly glistening and reflectively iridescent black slime which clung thickly to those headless bodies and stank obscenely with that new, unknown odor whose cause only a diseased fancy could envisage—clung to those bodies and sparkled less voluminously on a smooth part of the accursedly resculptured wall in a series of grouped dots—we understood the quality of cosmic fear to its uttermost depths

Damnably; extremely.