I began our Bujinkan class with 擲返 Tekigaeshi. In this form your defense is an attack. This attack to 脇壷 wakitsubo loads the opponent’s balance so you may knock him over with your kick.
I shared details about a class I had in Japan with Hatsumi Sensei. He told us to 空気にするで Kuki ni tsurude, or make the opponent into air. You make his attack empty, then float him up in the space.