Declension table of ?avastra

Neuter	Singular	Dual	Plural
Nominative	avastram	avastre	avastrāṇi
Vocative	avastra	avastre	avastrāṇi
Accusative	avastram	avastre	avastrāṇi
Instrumental	avastreṇa	avastrābhyām	avastraiḥ
Dative	avastrāya	avastrābhyām	avastrebhyaḥ
Ablative	avastrāt	avastrābhyām	avastrebhyaḥ
Genitive	avastrasya	avastrayoḥ	avastrāṇām
Locative	avastre	avastrayoḥ	avastreṣu

Compound avastra -

Adverb -avastram -avastrāt