Luna Pen

the Luna Pen is a special transforming tool that Luna gave to Serena to help her on her quest. It allows Serena to disguise herself as anyone she asks by yelling "Disguise Power! Turn me into..." and then what she wants to disguise herself as.

In Birthday Blues Part 2 Luna gives the pen to Mina to disguise herself as Sailor Moon to trick Kaorinite and Senishenta and save Serena from having her Pure Heart Crystal.