Declension table of ?rudramantra

Masculine	Singular	Dual	Plural
Nominative	rudramantraḥ	rudramantrau	rudramantrāḥ
Vocative	rudramantra	rudramantrau	rudramantrāḥ
Accusative	rudramantram	rudramantrau	rudramantrān
Instrumental	rudramantreṇa	rudramantrābhyām	rudramantraiḥ rudramantrebhiḥ
Dative	rudramantrāya	rudramantrābhyām	rudramantrebhyaḥ
Ablative	rudramantrāt	rudramantrābhyām	rudramantrebhyaḥ
Genitive	rudramantrasya	rudramantrayoḥ	rudramantrāṇām
Locative	rudramantre	rudramantrayoḥ	rudramantreṣu

Compound rudramantra -

Adverb -rudramantram -rudramantrāt