Instance: Violet Hold
Box: 4x Ele shaman + individual deathknight
Gear level: blues/70 epics, DK in greens/blues pre-heroic
Difficulty: Problematic, one boss in particular.
Guide:

I only managed to encounter two bosses in there.

Lava Hound (Corehound boss) Not too easy, but very doable.

Grounding Totem farm is essential here, it will swallow a lot of his annoying fires. It is however a very mana intensive fight. I killed this boss on my third try by dropping groundings, then moving away from them. I kept watching everytime he threw a ball of fire, if they went to grounding totem farm I knew I was safe, if it was headed for me, I instantly had to move before the ball landed. Spreading out might be an option, but due to the fact you can see the ball coming before it hits I would suggest to stick together and act quickly. The dk I had with me got seriously bursted a few times and I had major trouble keeping him up, had to drop earth elementals near the end and nuke the last bit swallowing a mana potion. With a good geared tank it might be a lot easier, but it seriously wasn't with this tank.

The Ethereal boss (Problematic boss)
This boss summons unkillable adds that need to be avoided at all costs, at the same time you have to stick close to the boss with all chars and keep moving around a lot.
I tried about 5 times, I did not kill him. First three times we just took wrong routes, we got locked inbetween to adds, had to run too far from boss, got teleported and owned, as the adds will be teleported on you as well. The last few tries were close, but quite frankly, my tank was jsut too hard to heal, I had to waste way too much time on healing and did not have much time to dps at all. This resulted in us calling it, and decided to gear up a bit more for this heroic first.

Ekerem, the birdy man with two adds, easy if done right
Don't kill the adds, just kill the boss and then the adds. If you kill the adds the boss goes enrage and ravages your tank. Whilest we found a tank is easily able to tank all three, and without the boss enraging, it's an easy fight. Tank and spank, nothing to it. Easiest I encountered so far in Violet.