Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
luctĭfĭcus, a, um, adj. [luctus-facio], causing sorrow or lamentation, doleful, woful, baleful: clades, Cic. poët. Tusc. 2, 10, 25: Alecto, Verg. A. 7, 324: pavor, Sil. 6, 557: jubar, Val. Fl. 3, 292.
Neutr. as adv.: luctificum clangente tuba, Val. Fl. 3, 348.