Verses with the word mightily in the New Testament (4 verses):

Acts 18:28
For he mightily convinced the Jews, and that publickly, shewing by the scriptures that Jesus was Christ.

Acts 19:20
So mightily grew the word of God and prevailed.

Colossians 1:29
Whereunto I also labour, striving according to his working, which worketh in me mightily.

Revelation 18:2
And he cried mightily with a strong voice, saying, Babylon the great is fallen, is fallen, and is become the habitation of devils, and the hold of every foul spirit, and a cage of every unclean and hateful bird.