This is one of the four Warlock's pet Voidwalker's spells, purchasable via grimoires at the various Demon trainers throughout Azeroth.
Torment creates an unkown amount of threat on the Voidwalker's target so that it is more likely to attack the Voidwalker instead of the Warlock or his/her companions. This is Shadow-based, so 
[Curse of Shadow] will help your Voidwalker land Torment more often. It can be resisted, by the way, and does not guarantee that your Voidwalker will get aggro in a snap. It has a 5-second cooldown.
When set on auto-cast, the game's AI merely uses this on the Voidwalker's current target whenever possible. Because of Torment's cooldown, that means once every 5 seconds, which tends to eat up the Voidwalker's relatively small mana supply fairly quickly. It also recovers quickly when combat is over, but be advised.
| Rank | Level | Mana | Description | Cost | Base Threat |
|---|---|---|---|---|---|
| 1 | 10 | 15 | Generates threat from targeted mob. | n/a | 45 |
| 2 | 20 | 30 | Generates threat from targeted mob. | 20 | 75 |
| 3 | 30 | 50 | Generates threat from targeted mob. | 60 | 125 |
| 4 | 40 | 70 | Generates threat from targeted mob. | Template:Gs | 215 |
| 5 | 50 | 90 | Generates threat from targeted mob. | Template:Gs | 300 |
| 6 | 60 | 110 | Generates threat from targeted mob. | Template:Gs | 395 |
| 7 | 70 | 130 | Generates threat from targeted mob. | Template:Gs | 632 |
Template:Warlock Pets