Ok, this is fun. Out of all the demons I can summon, I hate the imp the most. Not for any other reason than it has major lip. Fortunately for me, because I prefer Affliction, I don't have to deal with Rupjub's tinny whining in
Wrath of the Lich King. On the other hand, Destruction
Warlocks will have to suffer them because they're the perfect pets for the tree.
Some basic stuff first... imps don't need a Soul Shard to summon, so it's great for lazy Warlocks. It also has a basic
Firebolt that you'll need to set to auto-cast because that's pretty much all it can do once you've toggled it to attack. Firebolt was nerfed to a 2.5 second cast -- up from 2 -- but there are a lot of talents that pump up the imp's DPS (including the silly
Demonic Power which brings back Firebolt's casting time to the original 2). It also provides a couple of group buffs -- the
Fire Shield, which is kind of like a Druid's
Thorns but with a Fire Resistance bonus; and
Blood Pact, a Stamina buff that used to get a Warlock grouped with the tank. Blood Pact has been changed to grant a health bonus, rather than Stamina, so it will no longer stack with
Commanding Shout.
Finally, an imp can
Phase Shift, a sort of self-
Banish that only breaks when the imp attacks. A Phase Shifted imp used to be standard for Affliction Warlocks with
Dark Pact, because of the imp's high mana pool and monstrous regeneration rate. That's all set to change in
Wrath, however, with the improvements to the
Felhunter. The imp blows things up, that's kind of its nature, so in
Wrath of the Lich King, if you're a Warlock that likes to blow things up, the imp is the demon that blows things up right with you.