When we have start getting to the higher levels(Runescape Gold), and you'll be able to start weilding and wearing rune. There are two monsters recommended for this level, a quick exp monster, and a moneymaker monster.
So you need make Rock Crabs for quick and monymaking by Chaos Druids. As we see Rock crabs are one of the best monsters for leveling up at this level, and having 500LP. And these monsters give a whopping 200exp each in Runescape.
Kill! this may not seem like much at first, but those numbers can stack up pretty quick. Rock Crabs which Very low Att, Str. Low Def. 500LP, Hits occasional 1's. You can get it in North-East of Relleka. You can get Sea-weed, Oyster, copper ore (noted). Rare: Gold Charm, Casket as well.
If you are lucky you can get these rewards which considered by one of the best exp monsters at this level(Runescape powerleveling). By the way Chaos Druids are great moneymakers, having a lot of herb drops, continues.