Eldritchly

...with a cortege of dead kings about them, and the blown breath of skeletons thrilling eldritchly in the silver flutes.

Source: wiktionary

The white eyeballs and white teeth of the horse, the panting flanks, the rigid legs all stood out eldritchly.

Source: wiktionary

With his co-editor Robert Shea, he became involved with the eldritchly comic Discordian Society, and together they eventually co-created The Illuminates.

Source: wiktionary