The Preserved Dead is a type of mummy that acts, in any way, like a stronger variation of the normal mummy. This type of mummy is found most often within the Tomb of Tal Rasha, along with the other tombs that pretend to be of his.
As expected, these Undead are very dangerous in large groups and players that usually perform the "room rush" tactic at a moderate to low levels should keep caution. They can be usually be found with Unravellers and Burning Dead. They can appear from a Mummy Sarcophagus, which can add on to the frustration of destroying them.
They also release poison gas on their deaths, which can harm the player for extended periods if exposed.