How to unlock Xu sugarcane in the card book of tower defense

Go and buy it directly. There is an old hotel man on the street map outside. When you should buy it there, or play with a map or a copy of the tower defense, sometimes there will be a wild uncle Xu. You can unlock it if you have a chance to catch it. However, whether in Yan Feng or in ordinary maps, Xu Shu is useless, and its practicability is not very high.