Brutal green dragons are found in the Ancient Cavern. To access the Ancient Cavern, the player needs to start the Pyre ship section of Firemaking in Barbarian Training. Brutal green dragons are much stronger relative to the Green dragons residing in the Wilderness, and use a melee and a magic attack that both hit into the 800s. Like almost everything else in the Ancient Caverns, these creatures are immune to poison. Brutal green dragons may be part of a slayer assignment if the player has to kill Green dragons. Visually, the brutal green dragons look very similar to Elvarg as with the green dragons examine text Must be related to Elvarg.
It had been thought that brutal green dragons (like Mithril dragons) dropped Chewed bones; which are necessary for completing barbarian training or getting a Dragon full helm gift from a barbarian spirit. However, brutal green dragons do not drop these bones, only their less-prized "mangled" counterparts. A Jagex Moderator has confirmed that only mithril dragons drop chewed bones.
Brutal green dragons were buffed with the patch notes of 19 June 2013. The buff gave them increased combat stats. This was because after the Evolution of Combat, Green dragons were much more dangerous to kill due to the new mechanics of the Wilderness, and botters were constantly killing Brutal green dragons instead.