Whenever the Ace of Spades is drawn, ending the current Turn, I place another black card into the deck which increases the number of zombie actions available. It doesn't change the odds that much, but it does spook the players.
That's a nice addition to rise the danger level of the game.
Must try it soon.
In my gaming group we have designed at least half a dozen new zombies for the AKULA game, including longtongues, soldiers, fatties, ragers, toxics, crawlers, smarts, etc.
thanks for sharing.