From Guild Wars Wiki
The Mummy Mask is a festival hat obtained from Mad King Thorn, in Kamadan, Jewel of Istan, during the Halloween 2007 event. Since 2012, it can also be obtained by exchanging one Ghoulish Accessory Token with Aahtan during Halloween.
- Cannot be dyed.
- Unlike most festival hats, a Mummy Mask obtained before the December 17, 2009 update can be upgraded with an insignia.