Also late, but FYI here's the one I use in my game: take a tarot deck (78 cards), remove the Tower card and replace it about 1/3 of the way through the deck. Drawing the Tower card is equivalent to the tumbling block tower collapsing.
Alternatively, if you want to remove the concept of a tower altogether (useful if you're adding other mechanisms and want to reduce the number of items on the table), add a joker card about halfway through the deck of playing cards. This one isn't exactly equivalent in terms of probability, but it's close enough.