Declension table of ?yasta

Neuter	Singular	Dual	Plural
Nominative	yastam	yaste	yastāni
Vocative	yasta	yaste	yastāni
Accusative	yastam	yaste	yastāni
Instrumental	yastena	yastābhyām	yastaiḥ
Dative	yastāya	yastābhyām	yastebhyaḥ
Ablative	yastāt	yastābhyām	yastebhyaḥ
Genitive	yastasya	yastayoḥ	yastānām
Locative	yaste	yastayoḥ	yasteṣu

Compound yasta -

Adverb -yastam -yastāt