I am learning piano phase but I don't have a partner so I've been hanging around the practice rooms getting literally anyone who's not busy to play it with me. First I lure them in with "it's 5 notes only" and we learn to play it together and they can't crash out because it's literally only 5 notes and they are playing the same tempo the entire time (it would be embarrassing). Because of this we actually do learn to play it (for short periods of time so far) and I can practice against another musician. This is awesome. I have a handful of people I can practice with and the piano phase army grows. Yay!