ほろぼしたそうだ
semehoroboshita sōda

Godan Verb (su)
Evidential Auxiliary

Expresses hearsay about a past event ("I heard that...") of 攻め滅ぼす

1. They say they destroyed [it/him/her].; It is said [they] attacked and destroyed.

Past/Perfective
Hearsay Evidence