It's been a few times when an enemy attacks me -> I play different events to boost my DEF stats -> i want to play 'Stop hitting yourself' and I just can't (doesnt give me the option), it's also pretty crucial in gambit/protection build (gather charges and hit back).
It seems that you can play this card if it's the first event in the defense phase but you can't play it after you played different event beforehand.
Note : Just tried it and it worked but sometimes it doesn't, it's like the response isn't detected