{Were loosed} (eluth(8873)an). First aorist (ingressive)
passive indicative of lu(935c), "were let loose." {Which had been
prepared} (hoi h(8874)oimasmenoi). Perfect passive articular
participle of hetoimaz(935c), to make ready (hetoimos), in a state
of readiness prepared by God ( 12:6  16:12  Mt 25:34 ). {For the
hour and day and month and year} (eis t(886e) h(9372)an kai h(886d)eran kai
m(886e)a kai eniauton). For this use of eis with h(8874)oimasmenon
see  2Ti 2:21 . All preparation over, the angels are waiting for
the signal to begin. {That they should kill} (hina
apoktein(9373)in). The same idiom in verse  5  about the fifth
trumpet, which brought torture. This one brings death.