Declension table of ?vastvantara

Neuter	Singular	Dual	Plural
Nominative	vastvantaram	vastvantare	vastvantarāṇi
Vocative	vastvantara	vastvantare	vastvantarāṇi
Accusative	vastvantaram	vastvantare	vastvantarāṇi
Instrumental	vastvantareṇa	vastvantarābhyām	vastvantaraiḥ
Dative	vastvantarāya	vastvantarābhyām	vastvantarebhyaḥ
Ablative	vastvantarāt	vastvantarābhyām	vastvantarebhyaḥ
Genitive	vastvantarasya	vastvantarayoḥ	vastvantarāṇām
Locative	vastvantare	vastvantarayoḥ	vastvantareṣu

Compound vastvantara -

Adverb -vastvantaram -vastvantarāt