Method - Sit right in their direction, keep away from the melee area and employ eagle-eye. They're likely to attack most of the time and RS gold your d'hide / arma will tank most of their magical strikes. The only damage you'll suffer most of the time is their ranged attacks.
I would suggest that first of all, you need to build a room for the throne and then build an upper floor on top of it. Then, build an oubliette room beneath it. Also, you need to construct an escape door within it. After that, there are two options for being able to enter It is possible to build a huge cave entrance built in a beautiful garden. A set of stairs within the room.
After building one of those two rooms you can decide to build another room below the first, and there should only be one choice for that. After you've built that room(s) you may build in normal construction mode, and build treasure rooms, dungeon-like corridors and connections, as well as any room from above you'd like to put down below.
Also, if you haven't done it, Love Story is a must. Love Story quest unlocks a brand new type of dungeon which comes with a multitude of new guards for dungeons that are available for you to put down, such as scarabites, iron dragons, black demons and more. And the majority of them cost less than the original Trolls, Hellhounds, and steel dragons and so on.. If I've missed something, please feel free to ask once more.
Lardar pretty much summarized the most efficient methods, but for a good plan , you'll need to know precisely what your level is.
Good luck! It's up to you how you'd like to go about it, personally, I hate runecrafting and don't want to spend the money, so I keep slaying at the minute for the effigies I can use for runecrafting. As well as assisting people with their RC effigies (91 onwards, I'd recommend this since it's free 30k rc XP a day)
I'd suggest using the penguins well to get a quick increase every week, because it will all add up in a large XP number for as long as it will take for 99 Runecrafting. Alternatively, when free trade comes back , we'll likely see the increasing of Air Law, Air, and Double nature running again as well, which could be the better option to simply sit in the altar for a while runescape 3 gold and have others deliver the essence to you.