DISCLAIMER: Your Steps and Tasks may be different
If You kill Growler rather than doing the Growler necklace side quest, Sgt. Alain will send you on a different side quest titled; "Growler Mace Quest."
A quick run down follows:
Sgt Alain sends you to kill Cyfwich Difwych. (Loc- 50043, 12549) Cyfwich is blue at 13 and BAFed (Brought a friend) two other mobs, a green bandit thaumaturge and a grey bandit.
After you kill Cyfwich and get the item you go to West Downs in Salisbury Hills, to deliver an item to Beria, Apprentice Smith. Note- Her full name is, "Beria, Apprentice Smith" I didn't see her at first as I was looking for an npc with the tag Beria which is much shorter.
Beria gives you something to take to Contyth, Apprentice Smith in Humberton, Black Mountains south. Contyth gives you something to take to his father, Mathien, at Snowdonia Station in Black Mountains North.
Mathien sends you to kill Erick Redbeard. He only spawns at night in a camp of Red Dwarf Matrons, near loc=51k, 41k, it is directly east of snowdonia station you go up a very small hill and then there is a depression filled with trees. You can't miss it at night because of the matrons.
One of the Matrons is linked to Erick Redbeard. Both conned yellow at level 13, so be prepared for a fight.
After killing them Mathien sends you to the Guards Armorer with something else to deliver. The Guards Armorer gives you something to deliver back to Mathien.
Finally you get the Growler Mace, All told I got about 3 to 4 bubbles of experience at 13.