Large Brilliant Shards. Needed for almost all good heirloom enchants, these items are in high demand. The news that heirlooms will soon be able to sent to other accounts on your same Battle.net account may also spike demand a bit. You've seen from my most recent Faidian Slip that I tend to farm my Large Brilliants in Lower Blackrock Spire.
But what about that guy who doesn't want to farm? He just wants everything handed to him like some entitled, laz-- Oh, wait, there's an app for that. I mean, a rare spawn.
Flux at Power Word: Gold mentioned in the most recent JMTC Q&A session that he often found The Behemoth patting around the entrance to BRD. I decided I would go find out just how quickly he respawned.
What I found was very encouraging! After killing him about fifty times I have pegged his respawn between 6.5 and 7.5 minutes. He always spawns in the exact same location and will always drop the Vilerend Slicer, a blue BoE fist weapon that DE's into a Large Brilliant Shard.
He sometimes will drop Runecloth, greens of various use, and basically anything else on that level's loot table for an added bonus.
He's level 50 and hits pretty hard on a target of his level but anything higher or an alt with heirlooms should be able to handle him without much issue.
What This Means to You
So how do we use this information? Well, it's not uncommon for people to camp an alt next to a vendor with valuable limited quantity items and the same can be done here. Due to his fast respawn he is pretty much guaranteed to be up at any given time, assuming no one else on your server takes this advice! Park an alt within the quarry and anytime you're switching characters, anytime you log in, and before you log out go give him a slap and get a Vilerend Slicer. Once a week take the alt to a mailbox and mail them to your enchanter. Voila, stacks of Large Brilliant Shards without moving a muscle.
Another option is to actually camp him. Now, this can be boring if you don't have much else to do but, say you've got bag fulls of cloth to turn into Netherweave Bags, or some other time consuming task. Consider doing it here for that extra added benefit. I personally have one account camping him while the other account is flipping auctions or crafting! It's an amazing passive way to farm shards without having to move a pixel!
Thanks to Flux at Power Word: Gold for mentioning this mob and getting me interested enough to check this out.
Below is a video that may be of interest. There shouldn't be any "new" information beyond what's in this article, but it will give you a nice visual of how to get to him, his spawn point, what he looks like, etc.