The Tiny Shale Spider is a companion pet that drops off of Jadefang, a rare spawn located in the Crumbling Depths area of Deepholm (level 82 - 83 zone). This companion will be somewhat of a challenge to obtain, even for the most experienced pet collector.
Expect a lot of competition for this companion as there will not only be other pet collectors, but also hunters and rare spawn seekers who will be after the creature that drops the pet.
Much like Mr. Grubbs, you will need to complete a prerequisite, the entire Therazane quest chain in the Deepholm zone, before you even think about making your way to Jadefang. The goal is to unlock the Therazane faction dailies. You will need an item from one of the dailies in order to reach the rare spawn and ultimately the tiny shale spider.
I won't be going into detail about Deepholm's quest chains, as there are at least two main branches before the Therazane chain. From what I can tell, you must complete the first two chains before the Therazane quests open up for you. Once you've finished, you will gain access to the Therazane dailies.
There is a total of 9 Therazane dailies, 7 of which are offered each day. At least 5 of these dailies seem to be constants, while the remaining 2 that are available each day are randomly chosen from 4 dailies that are on a rotation. (There maybe more than 4 dailies in rotation)
What does this mean? I haven't tested it out yet, but this could mean that you will have to choose between picking up the "special" daily necessary to reach Jadefang or doing the Pebble daily to complete the achievement instead. It's possible that you can pick up both the special daily and the pebble daily on the same day, but I have yet to see this occur. More on this towards the end of the post.
So what is this "special" daily that I keep mentioning? The daily is called 'Underground Economy' and it is handed out by Ricket, an NPC that's located within the Crumbling Depths. She's a goblin standing on the left side, near some mushrooms, as you enter and reach the first room. She may not always be there.
With this quest comes an item, Ricket's Tickers, that's needed to reach Jadefang's tunnel. If you read through the quest description you'll note that she says, "I've got a nasty habit of packin' the explosives a bit thick. Mind the kick." I think that should be a big enough hint as to how we're going to make our way to Jadefang haha.
Anyway, navigating through the tunnels can be somewhat tricky, and you can get lost quite easily the first few times you are in there. Here's a basic run down of where to go after picking up the quest:
Navigating through the Crumbling Depths
-- Continue going straight, deeper into the crumbling depths.You can clearly see the opening of tunnel 3, Jadefang's tunnel. Notice the sheer drop. This is what makes reaching the rare spawn from directly below impossible (from what I've seen).
-- Once you see the colossal gyreworm (level 85 elite, non-attackable) going in what looks like a round-about, hang a right and follow in the same direction that the gyreworm is heading. (NOTE: the colossal gyreworm will "eat" you if you get too close and you will suffer heavy damage from it if eaten. so watch the way it paths and try to follow its tail.)
-- You will pass by one dead end tunnel before finding yourself in a large cavernous room with many tunnel pathways to choose from. See image below.
(click the image for a bigger version)
-- As you can see in the image, there are three objectives; tunnel 1, tunnel 2, and your final destination, tunnel 3.
-- Head into tunnel 1 (far right tunnel).
-- At the first chance you have to make a left into another tunnel, do so. This should be tunnel 2. If at the end of the tunnel you see the image below, you're golden.
Side note: these directions can also be used to navigate and complete the Pebble escort daily since Pebble also spawns at the opening of tunnel 2.
I haven't tested out using the hunter ability, disengage, or the goblin racial, rocket jump, but I do know that the warrior ability, heroic leap, will NOT work from either directly below the opening, while on top of the miscellaneous objects/blocks nearby, or from tunnel 2. My guess is that the former two will not work as well.
As you may have already guessed, you are going to need to use Ricket's Tickers to fling yourself into Jadefang's area. In order to be tossed far enough to actually make it up and into the opening, you will need to jump onto the green object/block as pictured above.
Note: you CANNOT make the jump from tunnel 2 to the green block without a mount or some sort of boost to run speed (I haven't tested out the latter, aka: sprint or rocket boots). Thankfully, you can mount within the Crumbling Depths! You cannot fly, though. (There is a bug on the beta atm, that allows druids to fly within the crumbling depths. do not expect this to go live.)
Once you've made it to the green block, use Ricket's Tickers and place one down. Stand in the direction/angle that you wish to be hurled, and watch yourself soar through the air to land (hopefully) safe and sound within the rare spawn's tunnel.
You may need a couple attempts to get the direction and angle correct, but don't worry. The tickers don't appear to have charges so you can keep placing them until you've got it just right.
Finally, Jadefang the rare, green shale spider should be located at the very back of the tunnel. She (I call her a "she" because 'Jade' seems like it would be a very pretty girl's name :P) is a level 85, non-hostile beast. My level 82ish druid solo'ed her fairly easily. Also, I believe she has an 8 - 12 hour respawn timer, but I could be wrong.
The companion pet that drops off of Jadefang seems to be a 100% drop rate; this could change. I must also note that the pet is bind on pick up, which would kind of make the respawn timer useless information unless you're a hunter who's going after both the non-combat companion and Jadefang herself. :)
Some final notes, you can hold onto Ricket's daily for more than one day. In the event that this specific daily is offered to you but Jadefang is not present, you can save the daily for when she respawns. This is why I mentioned the Pebble daily earlier on in this post. Since there are four specific dailies that are in a rotation, the Pebble daily may not be offered to you so long as you have Ricket's daily in your quest log. But as I also mentioned earlier, it may be possible that the Pebble and Ricket dailies can be available to pick up on the same day.
So that's it! There may be other (better?) ways to reach Jadefang, but I've found that this way suites me the best. It takes some effort and patience, but in the end it's worth it. Despite being terrified of spiders irl (you would be too if you were massively allergic to spider bites!), I'm really fond of the Tiny Shale Spider. :)