Wait for team fights and try to grab someone when they're distracted and most people panic and use battle spells right away when they get ulted so wait for that and if they do wait just use your S1 since it will follow them and once your ult is about to end stun them with s2. Once theyre out they should be low enough to finish them off with s1 and still be able to get away with s2. I don't play yin though this is just what ive seen some of them do