Permitted races: Stygian
Weapons: Daggers, crossbows, and thrown weapons
Armor: Cloth and silk armor
The Demonologist is one of the few "true" casters in Age of Conan and is probably the class that most closely resembles a stereotypical mage. They specialize in offensive single-target and AoE (Area of Effect) spell damage, and have various defensive shields, stuns, and run speed buffs. They can summon a demon that will fight for the demonologist and provide his party with a small buff depending on the demon that is summoned. Many of the demonologist's spells also scale upwards with every level even if you haven't acquired a new rank yet so don't fret if you go some levels without any new spells. Your spell damage is determined by a combination of your magic rating and any specialization ratings (such as electrical magic rating). Just remember that Funcom has stated that this rating does not apply in PvP, in order to provide fairer player match ups.
The demonologist is arguably the best class in terms of ranged DPS. Their burst damage surpasses their necromancer counterparts. With their long spell range and powerful single-target spells, coupled with silk and cloth armor, the demonologist is the epitome of a glass canon. However, crowd control abilities like Storm Chain, Fiery Torment, and later Hands of the Underworld, as well as defensive shields such as Protection of Set and Planar Shift, give the demonologist useful defensive abilities to keep them alive in the hands of a capable player.
As with most mage archetypes, defense is going to be your greatest hardship. Even with spells like Protection of Set, the demonologist can be killed easily. For this reason you may find yourself a frequent target in PvP from classes trying to get an "easy kill". Also, the utility of the demonologist's demon pet in PvP is debatable. The demon can act like a big red flag that says, "Hey I wear cloth kill me first". For this reason many demonologists don't even bother to use their pet in PvP as the small buff often isn't worth the aggression one will generate from enemy players. So if you want to play a pet class then look toward the necromancer because your demon will always be a utility at best.
The basics of the demonologist class are fairly straightforward; damage, damage, damage! At maximum range you will usually be able to kill a single NPC (Non-Player Character) before they reach you, especially if you are conflag speced, but to best utilize your DPS I'd suggest pulling 2-4 NPCs at a time and focus on AoE spells to bring them down. Since your AoE spells are on a timer be sure use single-target spells on the NPC with the highest health while waiting for your AoE spell to recharge. Make sure you keep all your shields up and never pull more than you can handle; start with two and add more as you get comfortable with your spell combos. Remember you can always have one spell in queue while your previous spell is being cast so choose your second spell while you're still casting your first to make best use of your casting time.
PvP is much less straightforward and your tactics will differ depending on the class and the skill of the player you are fighting. Always keep a hefty supply of health and stamina potions, and use them liberally. Since CC (crowd control) will be an integral part of your PvP arsenal, be familiar with what types of CC to use and when to use them. For example, rooting a player using Storm Chains will provide that player with a 60 second immunity to roots after the spell wears off so don't bother trying to recast it or any other root spells for that matter until the immunity wears off. However, you can still cast Fiery Torment and stun the player since that CC isn't considered a root. Just remember that they'll gain a stun immunity now as well. For this reason it is important to balance your CC abilities and space them out as much as possible. Also make the most out of knock back abilities like Thunderclap and Wicked Bolts if you are Havoc specced.
You will acquire different demons as you level, though this may be confusing because the demons will look almost the exact same. Trust me they are (slightly) different. Below is a list of the levels of obtainment, demon names, and their abilities:
The demonologist's two feat trees are Havoc and Conflagration. The Havoc tree focuses on improving lightning spells and provides the sorcerer with additional CC, pet buffs, and mana regeneration. The conflagration tree focuses on improving fire spells and provides more damage bonuses, especially single-target damage, as well as buffs, and additional fire damage over time. One nice thing about demonologist feat trees is that both are very viable options. Which tree you decide should be about personal preference. Regardless, there are important abilities in both trees that a demonologist should not overlook. For Havoc casters, Wicked Bolts and Thunderclap are necessities. Possession, Bombardment, Demon Heart of Chathba, and Earth Recharge are also very useful feats. I'd suggest investing a lot of your points in feats that improve your lightning damage or lower recharge time such as Rapid Recharge, Chained Shockstrike, Overloaded Shockblast, and Discharge Shockstrike. If fire is your bag then you'll obviously want to focus on feats that increase our DPS like Pyromancer, Amassed Flames, Flame Body, Lingering Flames, etc. Gate of Hell is also a necessity as that is the only feat-related CC in the conflag tree as of right now. I would also recommend investing some points into the Mage general feats tree especially in feats that will increase the effectiveness of your main defensive shield, Protection of Set, such as Mirrored Iron and Quickened Iron. Purge is also a very valuable feat, especially if you PvP with friends.
The Demonologist has seen a lot of changes since the game's release. Currently the Conflagration tree is being reworked on test center to include additional utility and crowd control. So always go with what you think will be fun. What is overpowered now probably won't be in a month, especially with additional PvP patches and more changes on the horizon.