He simultaneously leaked the location of their headquarters to the most powerful enemies of the court he could find, and it wasn't just them, since the court had a list of the targets they had assassinated on behalf of the father-daughter duo, he leaked that information too to their competitors and the organizations that had lost members to the assassination as a few of them were just as powerful as the Sentinel Birchwood Pavilion.
The list of enemies both organizations had was not small, but out of prudency, using the hundred-star treasure hall pavilion as a go-between, he had the information leaked to the Order too.
As for him, he had spent the better part of fifty years breaking apart the techniques of the Night Viper Court and learning all manner of arts that could subdue them. In as much as he was borrowing other people's hands, he wanted to be the one to sink the final dagger through them.