Since you ask a general question:
Brief:
Warlocks are masters of shadow, flame, and demonic power. They are a robed class that excels at plaguing their enemies with disease or curses, hurling bolts of fire or shadow energy across the battlefield, and summoning demons to aid them in combat. While warlocks are powerful casters that deal damage from a distance, their demonic powers can also protect or support their allies in battle, or even summon other players from across the world using ritual magic to conjure portals.
Warlocks have both powerful damage spells (primarily dealing over time) and debuff spells that work well in conjunction with each other and with the abilities of their group mates. They have Curses for many occasions; in fact, they can easily be considered the best debuffers in the game. Their pets, too, help with the damage dealing and grant the Warlock extra abilities to put to use. They can also control crowds well with Seduction and Banish, and provide limited support in the form of their summoned stones.
Tips:
Now that you know the basics of the Warlock, you have to learn how to play the class. At the start of combat, you will likely want to cast your DOTs and tell your pet to attack the enemy. Next you will cast other spells and possibly Drain Life to bring your health back up. Then, if you want a Soul Shard, you will need to cast Drain Soul right before the monster dies.
# Cast several DOTs on the monster, then cast Fear on it. As the monster runs away, hit it with direct damage spells.
# Use Fear if you pull too many monsters at once. Be warned that fleeing monsters may bring friends back with them, so use Fear carefully.
# Demon Trainers sell grimoires which you can buy even without the pet. You can right-click on it at any convenient time with the proper pet summoned to teach the pet the new spell.
-This is all from WoW and what i used for my char.
Brief:
"Hatred is my power and execration is my life. You will feel the real power of my curses when you are full of hatred."
There are many kinds of magic in the world, and they have developed in different shapes. Most magic uses strong force or shocks people to show their power. However, the so-called "Warlocks" are known to achieve their goals by placing curses on enemies, weakening their capability, or reducing their will to fight. Since their skill is based on Wizards' skill, they use mana, too. Wizards utilize mana to control elements of nature, whereas Warlocks utilize mana to enhance the power of hatred and thereby to reduce the power of enemies. They gradually destroy the power of enemies by placing curses, weakening, paralyzing them and putting them in chaos. They also utilize Wizard's skill to control elements of nature to directly damage enemies and make them in abnormal status. In addition, they have a skill to utilize blood to weaken enemies. For example, they take blood from an enemy to recover their strength.
- From Silkroad
and I will be making a Warlock guide later down the road. so stay tuned.
-Next time, browse the web then ask a more detailed question ^^.
Thanks
