Hulking Deathroc

Deathrocs are stitched monstrosities from the discarded viscera, bone, and organs that were not required to construct soldiers for the House of Constructs.

Riding Requirements:

This mount is available to all eligible characters on your account.
Level 10
Apprentice Riding (ground)
Expert Riding (flying)

Source:

Violet Mistake in House of Plagues, Maldraxxus.

Notes:

This purple deathroc has a small chance of dropping from the Violet Mistake, a specially-summoned NPC that appears at the Pool of Mixed Monstrosities (59,74) in the House of Plagues, Maldraxxus. To summon this rare you should be familiar with the mechanics of the Pool of Mixed Monstrosities and achieve a purple (even balance of blue and red ingredients) mixture. Essentially, you need to kill red and blue slime creatures in the area and pick up the materials they leave after they die (Viscous Oil and Mephitic Goo, respectively) and add them in even amounts to the pool until it reaches an ingredient count of 30. It is also allowable to add some yellow ingredients (Miscible Ooze) to the pool, providing that the amount of yellow remains lower than the other two colours. This means that you must add between 11 and 15 each of red and blue ingredients, and 0 to 8 yellow (and the amount of yellow must be an even number). The Violet Mistake will spawn as soon as the addition count reaches 30, providing the pool is purple.

Note that this pool is a communal effort and it's possible another player will show up and unwittingly mess up your mixture balance.