I've tried to do this a few (>7) times in Antiquities, always to redesign it into something else because it's just too edge-casey. Don't let that stop you, though.
My issue is that it then because either 1) a reaction to attack cards but only a few of them, if it only triggers when someone else tells you to reveal a card.
2) a reaction that triggers on your own turn, which is sort of a "choose one" thing.
The real issue, though, is that if you make it "explicitly when you reveal a card" then it doesn't trigger on "Look at" which is a problem, because now you either have to say "trigger on reveal or look at" but then the player has to reveal it to trigger it? Messy.