Frost Moon

Frostmoon is an event that can be triggered in Hardmode through the use of a Naughty Present. It is the Christmas counterpart of the original Pumpkin Moon with increased difficulty, making it the most challenging event introduced thus far. It has 15 standard waves as well as 5 extra bonus waves.

During this event, the moon changes color to look like the face of a snowman.

This is a very good source of Presents