A pile of salt or a bag of salt, (Bag of salt is obtainable from the G.E or slayer master, Salt shaker in the tool belt doesn't work) or an empty bucket to obtain a pile of salt
Mummies (level 70) and Scarab swarms (level 12) are not required, but aggressive nonetheless.
General tips
After returning the Canopic Jar and talking to the priest, you can enter the city through the front gate, so you can use the magic carpet transport.
It is possible to get out of the city without purposely dying, finishing the quest, or using a teleport. There is a small crack in the north-eastern corner of the wall near the locust. You can re-enter the city from a rock north-east of where the quest started, directly north-east of the tent where the wanderer is.
3-4 waterskins are recommended- remember, one will be taken from you by the wanderer right at the start. You will not need water within the city, and there are places to fill your water.
Note that wearing a lot of weight will make you die faster in the desert. Take this into account- bring more waterskins if you are bringing a lot of armour and weapons with you.
Note that jumping the pit is risky. You will not always make it, even if you have 100 run energy and nothing equipped.
If you wear the Amulet of Catspeak and talk to your cat, you can watch a final cutscene where you are first hypnotised by the wanderer and given an unholy symbol. Your cat will then explain to you what the wanderer's plans were all about.