Declension table of ?astramantra

Masculine	Singular	Dual	Plural
Nominative	astramantraḥ	astramantrau	astramantrāḥ
Vocative	astramantra	astramantrau	astramantrāḥ
Accusative	astramantram	astramantrau	astramantrān
Instrumental	astramantreṇa	astramantrābhyām	astramantraiḥ astramantrebhiḥ
Dative	astramantrāya	astramantrābhyām	astramantrebhyaḥ
Ablative	astramantrāt	astramantrābhyām	astramantrebhyaḥ
Genitive	astramantrasya	astramantrayoḥ	astramantrāṇām
Locative	astramantre	astramantrayoḥ	astramantreṣu

Compound astramantra -

Adverb -astramantram -astramantrāt