Broke Back Precipice

These are level 100 rare mobs that you can find on the Broken Precipice, Bonebreaker and Durg Spinecrusher can be killed and will award you progress towards your achievement despite you not being on the garrison daily quest.

The rare mobs needed for the achievement:

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• Bonebreaker
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• Pit Slayer
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• Durg Spinecrusher
• 
  

Bonebreaker and Durg Spinecrusher seems to be on a ~30 min respawn timer, independent of one another.

Pit Slayer is summoned by "smashing" the head on the pike that is located in the arena styled area of the precipice. He will then show up in the pit, somewhere around 38.80 13.80.

Thanks to OnderInvloed and jait for additional information!

I will reserve myself should any of the information above not be true or correct to 100%, feel free to comment below and I'll make sure to add/correct it.

Was looking through old acheivements I didn't have and Broke Back Precipice was one of them. It seems you can only complete it if the Assault on the Broken Precipice daily quest is up, and for me it wasn't.

I was able to go to my garrison and buy this missive from [npc=78564] who is outside of my Town Hall for 200 [currency=824] and this triggered the daily quest.

Job done.

I know this is old content now, but this may help someone like me who was wanting to get the acheivement and wasn't aware how to complete it if the daily quest wasn't up.

We were not able to summon Pit Slayer at his pike when it was a non daily day.

Bonebreaker was up tho.

~28 minutes later after killing Bonebreaker I checked for Durg Spinecrusher and he was up patrolling the western area.