So this Draenei Death Knight goes on and on about how wonderful it is to be undead and how everyone should try it, but two of her pets are actually Beasts? Go figure!
In any case, if you have a Mechanical or two, go ahead and try her at Level 12. Otherwise, it’s probably better to wait until your pets are Level 13. She’s not that difficult a fight, but you still need enough hit points to survive. Also, there aren’t any stable masters in the entire zone. Which makes this place annoying.
Carrion is more Beast-like than the other big giant worm thingy you fought at the last trainer, but not by much. Mainly, he just puts Acidic Goo on you to make you take extra damage then Leaps and Chomps until one of you is dead. Annoying, but not too tough.
Bleakspinner is another beast. Keep critters away from him. He has a normal beast attack (Strike) and two spider attacks: Sticky Web, which snares your pet, and Brittle Web, which damages your pet every time it attacks. The key to this pet is to use large attacks. Dots or other small attacks will hurt your pet more than they hurt Bleakspinner.
Plaguebringer is an undead fawn. All of her attacks are undead, so keep humanoids away from her. If you have a Critter or an Aquatic pet (especially one that does critter damage), she is easy mode. Most of her attacks are damage over time, so a shield ability is also good. She’s not really that tough, but you will fight more annoying ones like her later on.
In summary, this is not a tough fight unless you have a Critter- or Humanoid-heavy team. It’s super easy with a Mechanical, but you shouldn’t have too much trouble with most groups even though your pets may not all survive.