We get a pet of some sort every ten levels:
- 4: Imp: A ranged-DPS pet that buffs your party, and can avoid being killed with Phase Shift.
- 10: Voidwalker: A middling tank pet, with poor DPS.
- 20: Succubus: A good melee-DPS pet with the ability to CC humanoids.
- 30: Felhunter: A middling DPS pet that has the ability to devour magical debuffs as well as silence enemy casters.
- 40: Dreadsteed: A freebie mount!
- 50: Felguard (with talents): An excellent tanking pet with high DPS capability.
- 50: Infernal: A great DPS with higher health and better survivability than anything else you've got. (Enslave.)
- 60: Doomguard: Highest damage and health pet, plus an AoE, dispel, cripple (a slow), and war stomp (does damage and stuns). (Enslave.)
But while the first three pets (or four if you spec Demonology) are useful, and who can say anything bad about a free mount, the next two leave something to be desired -- because when they're summoned, they're not under your control, and the enslave mechanic is messy and difficult.
The Enslave Demon skill, which you use to capture these free-spirited demons, is on diminishing returns. What this means, in a practical sense, is that you can enslave a demon three times in a row -- after which it will become immune to future casts of Enslave Demon. Enslave lasts a maximum of five minutes but can break early (and likely will if this isn't your first cast).
So, what this means is, even if you summon and enslave an Infernal or a Doomguard, you'll get five minutes (or fewer) of reliable control before you need to recast enslave. When you recast, you'll get a maximum of five minutes of control, and while I can't tell you exactly how many minutes it will last, it's likely to last far less than five minutes. When you recast, you'll again get a maximum of five minutes of control, but it's still likely to last far less than that. And if you try a forth time? Immune. Practically, you're likely get about 10 minutes out of any enslaved pet.
So what use are you going to get from a pet for ten minutes? I say next to none -- once you summon them, that's just not much time to do anything with them. They'll last you a couple of pulls in any instance, but can turn on you unexpectedly at any time, being as much of a liability as an asset. The problem is the same in PvP -- they'll be incredibly useful for a little bit, but the fact that enslave can break at any time means they're just as likely to be smacking you around as your opponents. Yes, they're powerful enough to turn the tide of a fight, but it's impossible to tell whether they'll turn it in your favor or not. Because of their unreliability, I say that the Infernal and Doomguard novelty pets at best. They're pretty, and amusing to pull out once or twice -- but then you go back to the pets you can count on.
At this point, the question anyone should have is -- but do Warlocks actually need more reliable pets? I'd say yes -- because at present, we really don't have any raid-viable pets. And, as with Hunters -- pets can make up a large portion of our damage. When you have the Warlock without the pet, you're just getting part of what they're capable of.
So what could solve this problem? Well, I think the Infernal and the Doomguard are both too powerful to be permanat-summon pets. (Compared to our other pets, they're quite mean and nasty.) And I'm guessing that if Blizzard made weaker versions of them available as permanat pets that they'd wind up with the same problem our other pets have in raid situations -- they'd be too fragile, and fall over long before any boss was down.
If enslave were more reliable (i.e. not on diminishing returns), they could be usable long term -- at the high cost of a soul shard an enslave. But I'm guessing Blizzard doesn't care for this option -- because enslave didn't always have diminishing returns. But perhaps there's a happy medium between "no diminishing returns" and "three enslaves before it's immune diminishing returns." If you could keep control of these demons for a half hour or an hour, that would be long enough to put them to some interesting uses. (Though, again, it might be overpowered.)
Perhaps the solution is an entirely new pet -- a permanate summon to solve reliability problems, with high enough health or damage mitigation to allow it to do more than just fall over as soon as it was summoned in a raid instance. Something designed specifically to give a Warlock a raid-viable option other than the Imp -- who's only raid viable so long as you don't command him to do anything beyond follow you.
But what's your opinion, fellow Warlocks? Are pets a real problem? And if so, what's the solution? New pets, more pets, or just a revisiting of the pets we have?