Araj the Summoner. You may use Lang's Hand Grenades to destroy Stickbone Berserkers.
With the animus destroyed, the next logical step is to take out Araj himself, and to take a shard of his phylactery. You've probably already seen him, lurking at the fountain in the center of town.
Take my grenades with you. They won't do anything to Araj, but if he decides to summon any of those skeletons, you can use them to blow them away. Again.
Araj is a formidable opponent. Be prepared.
Araj dead... this is good. That gnome has done his part in winning this war. As have you, <name>.
You will receive:
Part 1 - The first battle for Andorhal
/  The Battle for Andorhal /  Hero's Call: Western Plaguelands!  Warchief's Command: Western Plaguelands! Both of the following, in either order:
All of the following, in any order:
(breadcrumb)  Victory, For Now
Part 2 - The uneasy calm
/  Uther's Blessing  Latent Disease
/  The Abandoned Crypt  Who Needs Cauldrons? /  Ambushed!
 Lower the Boom
/  The Writhing Haunt  Strange New Faces
/  This Is Our Army  When Death is Not Enough  Combat Training
Part 3 - The mending of the Plaguelands
The Menders' Stead (quest) (breadcrumb)
 A New Era for the Plaguelands
 Zen'Kiki, the Druid  A Different Approach
Part 4 - Living in the Plaguelands
(breadcrumb)  Northridge Lumber Mill
 Learning the Ropes
 This Means WAR (Wild Arachnid Roundup)
Part 5 - Hearthglen
 An Audience with the Highlord
 It's About Time!  Drudges... <Sigh>
 Taelan Fordring's Legacy
 Unusual Behavior... Even For Gnolls
 The Good People of Hearthglen
 Bagging Bisp  Turning Yourself In
Part 6 - The renewed plague
 The Long Trip Home  Memories from a Lost Past
 Gahrron's Withering Cauldron
 Return to the Stead
 Desperate Acts  Students of Krastinov
Part 7 - The battle resumes
(breadcrumb)  The Battle Resumes! Both of the following, in any order:
/  The Depravity of the Forsaken  Lindsay Ravensun, Revealed Both of the following, in any order:
/  Aradne  Andorhal, Once and For All /  Alas, Andorhal  The Reckoning