Rejoice is εὐφραίνου [euphrainou] , an imperative command, you all be glad! Heaven rejoiced when the devil and his angels were cast out (Rev. Rev. 12:12+). Jeremiah prophesied that in the day that God destroyed Babylon the heavens and the earth and all that is in them shall sing joyously over Babylon (Jer. Jer. 51:48). The MT and NU texts have saints and apostles instead of holy apostles.
The apostles and prophets, leaders of the saints of all ages, who have, themselves, borne the brunt of the worlds hatred, are given special prominence in the rejoicing. . . . Take Paul for an example. He pointed out that he and the other apostles had been chosen by God for special sufferings [1Cor. 1Cor. 4:9-13].1God has avenged you on her
Has avenged you on her is ἔκρινεν ὁ θεὸς τὸ κρίμα ὑμῶν ἐξ αὐτῆς [ekrinen ho theos to krima hymōn ex autēs] , God has judged the judgment of you against her. God has pronounced on her the judgment she wished to impose on you.2 A great multitude in heaven rejoices at the destruction of The Great Harlot which is said to be Gods vengeance of the blood of His servants shed by her (Rev. Rev. 19:2+). She is drunk with the blood of the saints and with the blood of the martyrs of Jesus (Rev. Rev. 17:6+) because in her was found the blood of prophets and saints, and of all who were slain on the earth (Rev. Rev. 18:24+). This is Gods answer to the prayers of the martyrs revealed at the opening of the fifth seal (Rev. Rev. 6:10+) and the prayers offered upon the altar of incense prior to the trumpet judgments (Rev. Rev. 8:3-4+). The song which Moses taught Israel prior to crossing into the Promised Land ends with the promise of Gods vengeance concerning the spilled blood of His servants: Rejoice, O Gentiles, with His people; for He will avenge the blood of His servants, and render vengeance to His adversaries; He will provide atonement for His land and His people (Deu. Deu. 32:43). As Jesus said in his parable of the unjust judge, And shall God not avenge His own elect who cry out day and night to Him, though He bears long with them? I tell you that He will avenge them speedily (Luke Luke 18:7-8).
2 Frederick William Danker and Walter Bauer, A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago, IL: University of Chicago Press, 2000), 450.