Declension table of ?tastuva

Neuter	Singular	Dual	Plural
Nominative	tastuvam	tastuve	tastuvāni
Vocative	tastuva	tastuve	tastuvāni
Accusative	tastuvam	tastuve	tastuvāni
Instrumental	tastuvena	tastuvābhyām	tastuvaiḥ
Dative	tastuvāya	tastuvābhyām	tastuvebhyaḥ
Ablative	tastuvāt	tastuvābhyām	tastuvebhyaḥ
Genitive	tastuvasya	tastuvayoḥ	tastuvānām
Locative	tastuve	tastuvayoḥ	tastuveṣu

Compound tastuva -

Adverb -tastuvam -tastuvāt