Huntress' duel with Shiva in issue 6 of the 2010 relaunch. It's a fight no one but Cassandra Cain has ever won fairly, and she knows it. And yet she manages to floor Shiva once. Floor her. Using her own blood. Shiva thinks this is so awesome, she dubs Helena the "Iron Owl."
The ending of Cry for Blood is both this and a Tear Jerker. Helena achieves what is probably her greatest triumph: she arranged the murder of Santo Cassamento, leader of one of Gotham's five families also her real father, at the hands of her uncle, Tomaso Pannessa, the leader of another of the five families, while also arranging for Panessa to be caught red-handed by the police, ensuring that he will go to prison for this, simultaneously decapitating two of Gotham's five families, and she has done this under the noses of Batman, Nightwing, Robin, Oracle, and especially the Question. Of course, in the process, she has betrayed their trust, especially the Question's, and burnt all her bridges. She is totally triumphant, and just as totally alone.