Declension table of ?tamasvan

Neuter	Singular	Dual	Plural
Nominative	tamasva	tamasvnī tamasvanī	tamasvāni
Vocative	tamasvan tamasva	tamasvnī tamasvanī	tamasvāni
Accusative	tamasva	tamasvnī tamasvanī	tamasvāni
Instrumental	tamasvanā	tamasvabhyām	tamasvabhiḥ
Dative	tamasvane	tamasvabhyām	tamasvabhyaḥ
Ablative	tamasvanaḥ	tamasvabhyām	tamasvabhyaḥ
Genitive	tamasvanaḥ	tamasvanoḥ	tamasvanām
Locative	tamasvani	tamasvanoḥ	tamasvasu

Compound tamasva -

Adverb -tamasva -tamasvam