Any nerf that Haunt received short of removal was well deserved, in my opinion. It was easily the best move in the game for a "free" pet, and not by a small increment either. While I didn't want to see the valk completely wrecked (and it isn't, even with the nerf), something had to be done. Here is something that I was trying to get the devs to look at many months ago, but I never got a reply from the official forums and I wasn't going to get a twitter account just to complain about OP pets in pet battles. From what was written, you can tell it was cobbled together some time ago (Anub has been nerfed in a manner of speaking twice since then for instance), but I believe that the changes to Haunt (and BP) are LONG overdue. The rant:
"I hate to sound like a complainer, but pet battles are really beginning to get frustrating with the proliferation of completely overpowered pets. It has gotten to the point where the only teams that I feel comfortable running are hard-counters to FotM groups (i.e. Unborn Valks/Death Adder Hatchlings/Murkalot/Anubisath Idol/Clonedancer setups, etc). There are some glaring problems with some of the pets that somehow continue to not be addressed. Let's take the Unbron Valk'yr for example.
The Valk is on so many teams that I almost never run without an Emperor Crab to "counter" it, which speaks badly of team variety options considering that we have hundreds of pets to choose from. The Valk is so ridiculous that many feel that they are handicapping themselves by not using it. The bad parts about this pet are two-fold; It has the perfect stat distribution to take advantage of it's abilities and racial, and it has one ability that in essence does seven-eight things in one button push. Let's break down Haunt a bit:
First it's tooltip "100% hit chance. The user transforms into an unholy spirit and enters the target, dealing 126 Undead damage every round. While haunting a target, the user is considered dead."
So what is so broken about this ability? First and foremost, it cannot be juked effectively as it has no cooldown. This is probably it's most egregious problem, but certainly not it's only one. Basically, the Valk user can just keep spamming Haunt until it lands with no thought for tactics or skillful application. Next, it does very stout damage for a DoT; among the best dmg per one-round ability in the game actually if it runs for it's full duration. Along with this, it acts as a "Dodge" of sorts for delayed damage moves such as traps and backline/same round DoT dmg, allowing both the Valk and the pet it swaps in to avoid such important damage. Yet another "hidden" ability built into Haunt is that it acts as the best self-pet swap in the game as it lets you choose your next pet to bring in, and has no cooldown. For a comparison, Feign Death does no damage, doesn't let you choose your next incoming pet, doesn't make you immune to all dmg, and has an eight round cooldown! This is why the Valk is often paired with another pretty broken pet in the S/S DAH, as a Haunt swap into the DAH completely moves the tempo into the Valk user's favor the vast majority of the time, which if you don't have the perfect counter setup to this duo(and even worse if they are fielding the SS Qiraji Guardling in the third slot),is pretty much the game right there in many scenrios. That's all of the possible problems with Haunt though, right? Wrong.
Haunt has some other built-in bonuses as well. The tooltip says that it "is considered dead for haunt's duration", and while this sounds bad, this is only very slightly a true "negative", and in many cases, is actually a large positive. While the Valk is moved to the back row and cannot be moved up again until Haunt has expired, it has effectively become immune to everything. This includes DoTs already applied to it before Haunt landed until it rezzes back up from Haunt, backline damage moves such as Dreadful Breath or Tidal Wave, delayed damage "unblockable" moves such as Sticky Grenade, and forced swap-in moves such as Nether gate (can't be brought back to the front). But wait, there's more! Haunt can also be abused by other pets as well because of how Consume Corpse works, and is a reason that Valks are often paired with Stitched Pups, Infected Fawns and/or Blighthawks. Since the Valk is considered a corpse, the Consume Corpse pet can use the big heal several times a fight (two-three times is about normal, but without Darkness running it will likely be game over by then anyway). I run into the occasional Valk/Blighthawk/Stitched Pup team. This team is obscenely strong, and beating it bascially requires an exact counter, with some luck thrown in as well, or the CC user is absolutely terrible. Chances are, if he or she is using this team, they know exactly how to use it making them well-nigh invincible in most scenrios.
So for the quick-and-dirty rundown of Haunt:
1. 100% hit chance (can't miss unless under an accuracy debuff or is Dodged)
2. No cooldown (cannot really be juked)
3. Makes traps, DoTs, delayed dmg, and backrow dmg against the Valk useless.
4. You can choose your next pet to bring in (no other swap-in ability works this way)
5. Complete tempo swing usually results in multiple wasted turns swapping Haunt soak pet with something else.
6. Effectively makes the Valk immune to everything while Haunt is running. Haunt is still doing it's damage so the Valk needs to perform no actions anyway.
7. Can be abused by Consume Corpse teams. I have the feeling that this is really more of an exploit than an intended mechanic.
8. High health pool and Undead racial allow Haunt to be used several times per fight.
I guess that is enough rambling for now. Of all of the overpowered pets, I believe that Valks are probably the worst. From some feeds that I have read, Anubisath Idols will continue to be OP for the foreseeable future, and Murkalot, well, is Murkalot. I am sorry if this is posted in the wrong place, and I would be happy to move this to the proper place where the devs can view it. Kovok and the Stunted Direhorn were nerfed because they were warping the "metagame", and the Valk is warping it even further because it is far easier to obtain, and thus is in far too many teams. In closing, I want to say that I appreciate the idea of giving harder-to-get pets "unique" abilities, but care should be taken to make sure that this uniqueness doesn't in actuality become "over-poweredness". Any discourse is of course welcome. Thanks for taking the time to read my wall o' text
Obviously, this was written in frustration, but I still believe that what I laid out was true. Even post-nerf, the valk is still useable in a tempo set-up, it just has to be used with care now instead of with impunity. In short, while the Haunt nerf "hurts" the user who leaned on it for wins, it helps the pet PvP community as a whole by opening up far greater flexibility overall.