Backstab

Backstab is a hard-hitting move that is performed from behind your enemy. The damage dealt is equal to 1.5 times your normal attack damage plus a flat amount of damage that varies dependent on rank. It only works with a dagger in the main hand.

Limitations

 * High energy cost
 * You must be behind and facing your target
 * Only available when a dagger is equipped in the main hand

Damage calculation formula
The basic Backstab damage formula: Opportunity = 1 + 0.1 * Opportunity Rank Lethality = 1 + 0.06 * Lethality Rank Surprise Attacks = 1 + 0.10 * Surprise Attacks Rank Aggression = 1 + 0.03 * Aggression Rank Blade Twisting = 1 + .05 * Blade Twisting Rank Modifier = Attack Power / 14 * 1.7 Normal hit = ((Weapon Damage + Modifier) * 1.5 + X) * Opportunity * Surprise Attacks * Aggression * Blade Twisting Critical hit = Normal hit * 2 * Lethality)

So a typical example: lvl 68 combat daggers rogue with a dagger averaging 106 average weapon damage, 1120 attack power, 2 ranks of Opportunity, the one rank of Surprise Attacks and 2 ranks in Lethality: Opportunity = 1.2 Lethality = 1.12 Surprise Attacks = 1.1 Aggression = 1 Blade Twisting = 1 Modifier = 136 Normal Hit = ((106 + 136) * 1.5 + 255) * 1.2 * 1.1 * 1 * 1 = 815.76 average damage Critical Hit = 815.76 * 2 * 1.12 = 1827.3 average damage

Improvements

 * Puncturing Wounds increases the critical strike chance of your Backstab by 10/20/30%.
 * Remorseless Attacks will give your next Backstab a 20/40% increased chance to crit after killing an opponent that yields honor or experience. The improved crit chance lasts for 20 seconds.
 * Opportunity increases the total damage of your Backstab by 10/20%.
 * Lethality increases the critical strike damage bonus of your Backstab by 6/12/18/24/30%.
 * Blade Twisting increases the total damage of your Backstab by 5/10%.
 * Surprise Attacks increases the total damage of your Backstab by 10%.
 * Aggression increases the damage of your Backstab ability by 3/6/9/12/15%.
 * Dirty Deeds increases the damage of your Backstab ability by 10/20% against targets with less than 35% health
 * Sinister Calling increases the percentage damage bonus of your Backstab ability by 1/2/3/4/5%.

At full rank of Opportunity, Blade Twisting, Surprise Attacks, Aggression and Sinister Calling, Backstab does 262.9% weapon damage.

Tips and tactics

 * When soloing, use Gouge to move behind the mob and then Backstab. This earns two Combo points off the bat! At higher levels it also combines well with Cheap Shot and Kidney Shot.
 * Humanoid mobs will often attempt to flee when they are low on health. When a mob does so, it will also often turn its back to you and keep running even though you are behind it, giving you the chance to perform multiple backstabs before the mob decides to fight you again.
 * If you want to use the Gouge-Backstab combo in the middle of a fight, be sure that your energy is full. Combined they use more energy than you have (unless you have Vigor). If you start the combo with less than 100 energy, you'll have to wait to regenerate some more. By that time the effect of Gouge will have worn off.
 * With the standard energy regeneration rate of 10 per second, it is viable to Gouge-backstab starting with ~70 energy. The 4 second duration of standard Gouge should give ample time to get into position and regenerate the minimal 60 energy required for backstab.  Though this may be technically possible starting with 65 energy, taking into consideration latency and user reaction, 70 is a safe bet.  Note this starting energy requirement is reduced with Improved Gouge or talents improving regeneration rate.
 * When grouped, you can get at a mob's back fairly easily. However, if you backstab whenever you can, you are likely to gain aggro, so use with some care. Consider using Feint or Vanish to keep your Threat level down.
 * In PvP, a common method of moving behind another character is to jump forward through them, hold your right mouse button and rotate in mid-air to complete a 180 degree turn. You will land right behind and facing your opponent ready to follow up with a quick backstab!