
Notes
To fight these you must be 77
Slayer and have received them as a Slayer task. They are non-aggressive, simply investigate the moving Mounds around the area and they will appear.
Charm Drop Rates 
Tactics
Melee armour is recommended. They don't hit very hard, but they have a special attack where they will burrow underneath you and rise up under you causing 300 damage. The attack is avoidable if you are quick.
Examine
I dread to think how many of these are in the sand.
Top Drops
Focus Sight, Clue scroll (level-3), Clue scroll (level-4), Magic seed, Dragon Spear, Starved ancient effigy, Dragonstone.
Drops
Waterskin (4), noted Yew Logs (10), noted Grimy herbs, Water rune (100), Uncut gems, Half keys, Super defence potion (2), noted Pure essence (120), noted Potato cactus (1-10), noted Adamantite bar (3), Herb seeds, Cactus seed, Belladona seed, Watermelon seed, Water talisman, Mind talisman, Fire talisman, Law rune (15), Mithril battleaxe, Rune hatchet, Death rune (15), Yew seed, Maple seed, Swordfish (2), Gold charm, Crimson charm, Green charm, Blue charm