Declension table of mantrin

Neuter	Singular	Dual	Plural
Nominative	mantri	mantriṇī	mantrīṇi
Vocative	mantrin mantri	mantriṇī	mantrīṇi
Accusative	mantri	mantriṇī	mantrīṇi
Instrumental	mantriṇā	mantribhyām	mantribhiḥ
Dative	mantriṇe	mantribhyām	mantribhyaḥ
Ablative	mantriṇaḥ	mantribhyām	mantribhyaḥ
Genitive	mantriṇaḥ	mantriṇoḥ	mantriṇām
Locative	mantriṇi	mantriṇoḥ	mantriṣu

Compound mantri -

Adverb -mantri