Declension table of mantra

Masculine	Singular	Dual	Plural
Nominative	mantraḥ	mantrau	mantrāḥ
Vocative	mantra	mantrau	mantrāḥ
Accusative	mantram	mantrau	mantrān
Instrumental	mantreṇa	mantrābhyām	mantraiḥ mantrebhiḥ
Dative	mantrāya	mantrābhyām	mantrebhyaḥ
Ablative	mantrāt	mantrābhyām	mantrebhyaḥ
Genitive	mantrasya	mantrayoḥ	mantrāṇām
Locative	mantre	mantrayoḥ	mantreṣu

Compound mantra -

Adverb -mantram -mantrāt