The Lunar Diplomacy quest is easy, medium length and is the only shop to sell astral runes for iron men and hardcore accounts.
You can use fairly minimal gear, as shown here, and bringing only a super set and sharks. There's no need to bring prayer or super restore potions because you cannot use prayer for this fight.
Start off heading to the Oneiromancer who is on the wall of quest NPCs south of the bank. Be sure to take a sip of your potions before beginning.
The first monster you fight is The Inadequacy (level-343). I've seen it can hit 15s, but fairly infrequently, kill it normally.
When The Inadequacy dies, you then fight The Everlasting (level-223) who I've seen hit 18s. Keep an eye on your HP, but it will die faster than the first.
The third wave is The Untouchable (level-274). Nothing special here, dies pretty quickly.
The final form in the fight is The Illusive (level-108). The easiest fight and you may take no damage during. The catch is that when it's under about half HP, it will burrow underground and reappear elsewhere in the arena. You can then get two hits in before it does it again. It's more annoying than anything.
Congratulations! You've completed the Lunar Diplomacy quest!
You gain access to the quest shop:
Astral rune: 160gp
Lunar staff: 30,000gp
Lunar helm: 15,000gp
Lunar torso: 120,000gp
Lunar legs: 80,000gp
Lunar cape: 12,000gp
Lunar amulet: 4,000gp
Lunar ring: 2,000gp
Zombies Supporter! 
10 Year Veteran 
