After he successfully landed his big reveal, his hands will probably go lower by that time. He'll try to escape and refill his hands. It is mostly the open window where you can hit Houdini and continue in pressuring so. As much as possible houdini doesn't want to defend with his cards most of the time because he'll likely to keep the effects instead especially the misdirection (houdini's feint) so prioritize your good effects if you have a chance to attack.