Personally, I'd suggest the Karamja dungeonwhich is located in the Tz-Haar zone
RS Gold. There's an array of choices for this There are a variety of ways to attack them right there with a standard weapon, food, or bunyip if you can. Or you could halberd them from a safe place, or make use of range from a safe place which makes it food-free.
The other option is a cannon you could try or on its own or with the combination of one among the options above. Of course, there are other locations, but I'd suggest this one to be sure. I've noticed that the title reads greaters, but the text refers to less.
If the job is superior, then my main recommendation would be the dungeon located in Brimhaven. It is possible to use any of the above options, though you have to fight the terror dogs as well. There's not a many options to choose from for bigger dogs (no no pun meant) However, you must continue to fight when it comes to those.
Take a trip to Lunar Isle to use pure essence at the altar until successful, then sell the runes you have on the Great Exchange, repeat. When you've reached 82 Runecrafting and you'll be able to create two runes for one essence
Buy Old School RS Gold, thus increasing your profit by twofold. Astral Rune is required to complete the Dream Mentor quest.