WoWDB

Disenchanted from Mists of Pandaria epics (except for holiday epics), and can be created by  Sha Crystal once per day.

An adorable little pet, though a bit expensive if you're not an SC2 player

Perfectly itemized for a 2H frost DK - haste + crit & crit bonus. Can socket a blue hit gem if you're low on hit

The mount reward does indeed require Cloud Serpent Riding from the Order of the Cloud Serpent faction

The coordinates for the crystal are wrong. They are just above the last K of Kypari Ik, or, in the center of the Panic Clutch, located at 55, 46

As said, this can't be interrupted, but stuns are useful. For a DK, use Asphyxiate, for a Warrior use Charge, and so on. If you can stun them, you can interrupt it. Otherwise, just move away

One of these in a group will swell to huge size. Their abilities can be interrupted, however, the enlarged Quilen will leave a 5% per stack debuff that cannot on the tank for armor. At 20 stacks, the tank will have no armor. It's recommended to swap between tanks at 10 stacks until the stacks fall off.

These guys are a DPS check for new entries. You have to DPS them down ONE AT A TIME as quickly as you can. Don't waste hero, but using cooldowns is recommended. Once both are down, you can continue on. If you fail, you reach 100 stacks of petrify (5 per second), and they reset.

The caches spawn randomly in the halls (and the achievement is misnamed to say "Vault Key"), but I can confirm you can use this at any rep (friendly right now), though the more unlocked areas, the easier it is to find a cache. Once used, the cache vanishes.

For me, I got 1 Spirit of Harmony, 1 Relic of Guo-Lai, and 21gold. The relic gave me 180 reputation with the Golden Lotus