Declension table of ?tastakvas

Neuter	Singular	Dual	Plural
Nominative	tastakvat	tastakuṣī	tastakvāṃsi
Vocative	tastakvat	tastakuṣī	tastakvāṃsi
Accusative	tastakvat	tastakuṣī	tastakvāṃsi
Instrumental	tastakuṣā	tastakvadbhyām	tastakvadbhiḥ
Dative	tastakuṣe	tastakvadbhyām	tastakvadbhyaḥ
Ablative	tastakuṣaḥ	tastakvadbhyām	tastakvadbhyaḥ
Genitive	tastakuṣaḥ	tastakuṣoḥ	tastakuṣām
Locative	tastakuṣi	tastakuṣoḥ	tastakvatsu

Compound tastakvat -

Adverb -tastakvat