I don't know why I haven't commented in this thread before. It is a VERY interesting mechanic.
However, having too many different type of cards can make you play a whole quantaless deck and that can be OP.
since there is only one track, you cant actually play a deck that is entirely Surprise cards. actually as it stands, it is far too limiting, but removing the track and making each card have its own counters would be too powerful, and i cant think of anything in between...
The thing about Surprise is that it's basically a 13th element since "there is only one Surprise cost 'track' per player."
and basically an element that you only have a mark for and no pillars...