Declension table of tapasya

Neuter	Singular	Dual	Plural
Nominative	tapasyam	tapasye	tapasyāni
Vocative	tapasya	tapasye	tapasyāni
Accusative	tapasyam	tapasye	tapasyāni
Instrumental	tapasyena	tapasyābhyām	tapasyaiḥ
Dative	tapasyāya	tapasyābhyām	tapasyebhyaḥ
Ablative	tapasyāt	tapasyābhyām	tapasyebhyaḥ
Genitive	tapasyasya	tapasyayoḥ	tapasyānām
Locative	tapasye	tapasyayoḥ	tapasyeṣu

Compound tapasya -

Adverb -tapasyam -tapasyāt