Merlin is a Premium Box Tsum. He is currently only available on the Japanese version. He was first introduced during the Japan event Disney Star Theater Classics (June 2020).
Merlin will transform into one of the other Tsums of your choosing for a short while. His base time is 4 seconds, and his base Score multiplier is x2.
You will be able to choose which of the onscreen Tsums you can transform into.