The other thing you could do that nobody has yet mentioned is to have a card that would say something like "MUST be played on turn X". That would be an extremely narrow card, but it would make for interesting possibilities.
This reminds me of a M:tG card, Serra Avenger, which was an undercosted creature but it couldn't be played on your first three turns. So, in turn trigger turns, it would say "Play only on turn 4 or later".
This could be a way to make me not hate earthquake/quicksand so much... :p Give it something so that it can't be played too early, like turn 1...