very weird situation with break open and morph card counter spell magic

[ralphy99]

I don't think the folks at Wizards thought of this situation when designing Break Open, but what if someone casts it (and its the only spell on the stack) targeting my Voidmage Apprentice? since the break open is the only spell on the stack it has to counter it? but then do I turn the voidmage apprentice back face down? and also now opponent knows what my morph card is even though break open was countered. Does he need to legally forget that the morph card is a voidmage apprentice, like for example would it be legal for him not to cast a spell because he knows I can counter it with the morph?

[Arix]

This is actually a lot easier than you think. The Apprentice's ability can't go on the stack until Break Open has fully finished resolving. By that time, Break Open is in your graveyard. So by the time you choose a target for Voidmage's ability, Break Open isn't on the stack any more, so isn't a legal target for the ability.

[Ninja]

how would you make him "forget" what your card was, hit him on the head, or maybe hypnotize him