Comment by vikingerik

I figured that out just from playing Tombstone City. It's the first paired cactus by scanning the board in reading order (each row from the top, left-to-right.) (You mean a cactus that turns into a monster, not a tumbleweed.) And yes, once you know that, the game is pretty easy when you can anticipate every threat. I remember being able to go for at least a couple hours in one game; don't remember if I ever rolled it over or got bored before that.