I bet you were facing a Black Luster deck, the guy must have used a Djinn in order to ritual summon, that's why your onslaught didn't work
I used it against Yugi Muto's sphinx effect which sends the card back to the hand. But it seems apparently it didn't work and still targeted my card.... I activated the card after ritual summoning Magician of BC.
Cyber Angels are so OP, they have so much INSANE draw engine and recycling, they don't need this skill or any skill apart from boring Restart or Balance for little more consinstency. And the deck is already crazy consinstency. I do not know what was Konami thinking releasing this into the game.