Henka Wasa is a basic part of Aikido. It is the art of changing from one technique to another technique. For the test the instructor calls out a technique to start with and the student then has to start that technique and then change to other techniques. In Randori Uke might counter the first technique so Nage has to change techniques or Nage might change techniques because of other attackers, the layout of the room, Uke's safety, or just for fun.