Your ability to land a blow effectively. Accuracy dramatically increases your accuracy, making every shot count. +5/10/15% to hit with all powers. When striking the first target of an attack(the primary target on AoEs), any amount that IS dodged is reduced by 5/10/15%, so a 50% dodge gets lowered to 40% with 2 accuracy. In addition to that, any HPbuffer on your enemy is pierced for 5/10/20% of the damage you would've dealt. This stacks with the identical effect from the Damage Combat Skill.
To understand Defense, you have to understand the whole defense system. The game makes a potential total of three rolls, each a 1d100, with any number at or below the target being a 'hit'. Included in accuracy is the your attack's base accuracy.
- The first roll is your Accuracy - the enemy's Defense - 45.
- If this hits, 100% of the damage is applied.
- The next is just your Accuracy - the enemy's Defense.
- If this hits, 75% of the damage is applied.
- The last is your Accuracy - the enemy's Defense + 30.
- If this hits, 50% of the damage is applied.
- If this misses, 25% of the damage is applied.
Here is an example! Using a power with 75% and player having +25 accuracy, against a target with 15 defense, it would look like this 75 + 25 - 15 - 45, for a target number of 40. If the 1d100 comes up as a 40 or less, then this hit is a success!
There are caps of course. The hard caps are such that your target number can never go above 95 nor below 5/10/15 (first/second/third roll). Next, the soft caps are at 50, 100, 150, 200, and so on. The first 50 give a 1 to 1 relation. After, 51 to 100, requires 2 points of accuracy or defense to add 1 effective point to either. Then 101 to 150 requires 4 points to add 1 effective point, and so on. Additionally, a power cannot have its accuracy increased or decreased by the Accuracy and AccuracyDebuff statuses to more than 4/3rds of its base accuracy or less than 2/3rds of its base accuracy (so the example power's 75% accuracy cannot be modified by the Accuracy or AccuracyDebuff statuses to above 100% or below 50%). Defense/DefenseDebuff is applied after any potential capping of Accuracy and has no such limitation. The Accuracy combat skill is treated as a reduction of 5/10/15 to the target's effective Defense rather than being subject to the Accuracy caps.
Mobs and Feral Mode players gain +5 Defense not shown in their effects list at Lv40, plus an additional +5 Defense per five levels afterward.
AOE skills suffer an increasing dropoff in accuracy with each successive target after the first. Larger AOEs have slower dropoffs, and the Controlled Burst combat skill reduces the rate of this dropoff.