Declension table of siddhi

Feminine	Singular	Dual	Plural
Nominative	siddhiḥ	siddhī	siddhayaḥ
Vocative	siddhe	siddhī	siddhayaḥ
Accusative	siddhim	siddhī	siddhīḥ
Instrumental	siddhyā	siddhibhyām	siddhibhiḥ
Dative	siddhyai siddhaye	siddhibhyām	siddhibhyaḥ
Ablative	siddhyāḥ siddheḥ	siddhibhyām	siddhibhyaḥ
Genitive	siddhyāḥ siddheḥ	siddhyoḥ	siddhīnām
Locative	siddhyām siddhau	siddhyoḥ	siddhiṣu

Compound siddhi -

Adverb -siddhi