What quest do you have to do for the magic spell "venngeance" in Runescape.?

I have seen 2 quests, Lunar Diplomacy and Dream Mentor. To do Dream Mentor you have to have done Lunar Diplomacy. They both unlock lunar spells but I was wondering which unlocks vengeance. I am making a pking account and this is one more thing on my list besides 99 strength. Then ill be ready to pk! Thanks for all of the answers.