The Ruthless Seven have sent a powerful demonic being to the Plains Of Havoc. Do you have what it takes to stop it?
Before the Summer Update 2009, the method to start this quest was rather different, as it did not require a Holy Icon but rather stepping on specific tiles. This method was never completely understood (even though the quest was completed then), and then the quest was modified to the current state. There was also a short period after the quest was initially introduced during which access to the Demon Oak was apparently much easier (and not as rare) than it was intended, so a patch was released to supposedly fix this.
First, you need to go to the Plains of Havoc and search for "the infested area" (here). It is surrounded by a lot of Dead Trees, east of Dark Cathedral and north of the vampire's house. There you will find a 1 sqm corridor that leads into the center (there is no Gate Of Expertise but you do need to be level 120 or above to be eligible for entry). If you have the Holy Icon with you, you will be teleported into the infested area.
Upon entering the area you will receive this event message:
It seems that you have discovered an 'Ultimate Challenge'
- The left spiked ball
- The bird
- The face of the tree
- The right spiked ball
Attacking these four points will anger the Demon Oak and cause him to summon monsters. Every time you attack one of the points, you will lose 300 hitpoints (Earth Damage). Once attacking the four points you will have to keep attacking that same area until it is "Dead" (it will "puff smoke"). Depending on which order you choose to do the four points the demon oak summons different monsters.
Here's the pattern:
- The face of the tree:
For hits 1-4 and 6-9 it's random if the demon oak summons nothing or 4x bonebeasts.
The 10th hit on the last of the four points is always 1x Demon instead of what should've spawned, i.e. if you do the face last you get the Demon instead of the Undead Dragon and the Hand of Cursed Fate, and if you do the left spiked ball last you get the Demon instead of the two Betrayed Wraiths and so on.
Once the tree is 100% dead, you may leave again. Upon exiting the area you will receive the Herbicide achievement and the following message:
Tell Oldrak about your great victory against the demon oak.
Thus, speak to Oldrak again to tell him you have defeated the Demon Oak. Once this is done, go to a grave stone which is located south of the infected area with the name of "Yesim Adeit" (Which can be read as "Yes I made it"), here. Use the Grave Stone (you may have to remove a Star Herb that spawns on top of it) to enter the rewards room and choose your reward.
Additionally, you are now eligible of obtaining second addon of Demon Outfits.