WoWDB

Step into any of the PX-238 Wondervort machines around major cities, transform yourself into a holiday gnome, and go wrack up your HKs by whatever means you prefer.  The buff does not persist through death, so I recommend queuing by a machine so you can reapply the buff after each game or arena.

This is among the harder achievements for this holiday event, so I recommend starting work on this one as soon as possible. As Tziva said, the buff does not persist through death.