- For general information about demonology, see Demonology.
Overview
- Main article: Warlock talents#Demonology
Demonology is the second of the Warlock's three talent trees. It is centered around improving the Warlock's minions, Stones, Stats and survivability as well as the warlock's two armor spells. The key talents include 
[Summon Felguard], 
[Soul Link], 
[Demonic Knowledge] and 
[Master Demonologist]. It is often taken at mid levels (40+) for Demonic Knowledge which provides a substantial increase in damage before much gear with +spelldmg is available.
Advantages
A Demonologist has larger health and mana pools, pets which deal more damage and can soak up more as well access to the infamous Felguard minion, which can be used as a DPS tank, DPS or offtank.
Demonologists have a much higher +spelldmg than other Warlocks due to [Demonic Knowledge] and 
[Demonic Aegis]. Their damage is further enhanced in some cases by [Master Demonologist].
Demonology is a viable tree to use when solo training, with talents such as [Soul Link] and 
[Demonic Resilience] improving the tanking ability of the warlock's active pet, as well as reducing damage taken by both demon and master.
Due to the large amounts of spell resistance granted by the [Master Demonologist] effect of the Felhunter minion, as well as the large amount of +stamina the demonology tree grants, they are arguably the best caster tanks and are able to generate threat quickly using 
[Searing Pain]. The Felhunter's 
[Devour Magic] and 
[Spell Lock] abilities, when used correctly (in some cases, in tandum with 
[Curse of Tongues]) also make them powerful anti-casters.
Demonologist's stones, if they decide to spec into those talents, are more powerful. The 
[Healthstone] which is in effect an extra potion, on a different timer which can be traded as well as the Healthstones generated from Ritual of Souls heal significantly more helping in raids. Both the Firestone and Spellstone are arguably more useful than wizard oils and other weapon-applied consumables, and the 
[Master Conjuror] talent further enhances them; the 
[Firestone] adds more +crit rating and the 
[Spellstone] adds more +haste.
[Master Demonologist] and 
[Demonic Sacrifice] give the Warlock a high grade of flexibility, offering multiple different effects, depending on the active or sacrificed pet. They allow the warlock to operate optimally in a wide variety of situations, making it possible to reverse a bad situation, such as a summoned pet near death, into somewhat of an advantage.
A demonology specced warlock can, through use of 
[Health Funnel] and damage-mitigating talents, solo many elite encounters. At higher levels, even some of the toughest non-instanced elites can be soloed with ease using the Felguard or Voidwalker as a tank.
Disadvantages
If a Demonologist's pet dies, their DPS is greatly reduced, much like a Beast Mastery Hunter.
Limited talents for mana efficiency.
There are no threat-reducing talents in the tree, although there are talents which allow the pet to generate threat more easily, keeping aggro off of the warlock.
Other Notes
One of the best tricks of the Demonology specialized Warlock is to use the Voidwalker's Sacrifice ability and then use 
[Fel Domination] combined with 
[Master Summoner] to summon a new minion in half of a second.
After release, it was looked down upon as not being useful, though this opinion is not as prevalent since the addition of [Master Demonologist]. More recently though, there have been calls by some that Demonology Specialized Warlocks need to be nerfed due to their increased survivability due to the Soul Link talent. However, since then, the Warlock class, and especially its Demonology tree, has undergone major changes.
See also
Affliction | Demonology | Destruction