[Nervous Tick]

>> in·cu·bus etc.

Right you are.

The adjective form of “incubus”, that is, “incubusical”, is not actually *in* the dictionary... but I found it emanating from one of the language’s penumbras. ;-)

[BibChr]

Well-struck. We’re ALL ABOUT penumbras here at FR.

[Red Badger]

Adding “-ical” or “-ic” to make a noun into an adjective is perfectly acceptable. Kind’a like “gerund-ing”..........