Silveroak is a rank 40 Treekin Hero boss. He is surrounded by six 'Silver Dryads' that are all rank 40.
Approaching the lair will trigger an Achievements unlock. (Not implemented yet)
From the bridge leading south out of Thorshafn, follow the river going southwest. Keep going until you see an area on the right that looks like a burned down forest. In this area, there will be a section of raised ground that you can only reach by going through a hollow log.
On this high ground, walk out onto the dead tree that hangs over the edge. From the tree, hop down onto a tree stump.
Carefully leapfrog between the nearby stumps, go up the branch on the last stump; you are now in Silveroak's lair.
Killing Silveroak drops 1-2 level 39 rare (blue) chest:
|Warrior Priest||Bright Wizard||Knight of the Blazing Sun||Witch Hunter|
|Archmage||Shadow Warrior||Swordmaster||White Lion|
|Shaman||Squig Herder||Black Orc||Choppa|
|Disciple of Khaine||Sorcerer||Blackguard||Witch Elf|