The guardian mummy starts the Pyramid Plunder minigame. To get to the mummy, players must go to Sophanem and find the pyramid that has 4 "anonymous looking doors" near the city's northern gate. Pick the correct door, which varies over time, to find the room the mummy is in, which is the starting point of the minigame. When opening a door, the mummy occasionally thrusts you back and does a little damage (mummy's bandaged arm pushes a player away from the ajar door).
The guardian mummy will recharge your pharaoh's sceptre or sceptre of the gods in exchange for some of the artefacts looted from the pyramid it guards. The mummy will not recharge any partially depleted sceptres, saying that it will not waste the King's magic on a partially depleted item. Noted items will not work in recharging the sceptres either.
Though the player who finds the pharaoh's sceptre can't see it happen (being ejected from the pyramid), the Guardian mummy (this time called Annoyed guardian mummy) briefly appears in some of the rooms when a sceptre is found. For a split second the mummy can be seen saying Grr, someone has found the pharaoh's sceptre! Right! That's it. I'm clearing all the urns and refilling them now.
Although the guardian mummy is a man, when speaking to Simon Templeton after completing the Dealing with Scabaras quest, Simon refers to the mummy as being a woman, as 'mummy' is British slang for mother.