Defiance
Description
Blasters' earliest abilities come so naturally to them, that they are accessible even in states that normally prevent them from using powers, such as being Held, Slept or Stunned. Additionally, each time the Blaster attacks with a primary or secondary power, they gain a stacking damage bonus for the next several seconds. The amount of the damage bonus and its duration is dependent on the exact power used, with single target abilities generally giving the largest bonus.
Detail
Even while a Blaster is mezzed, he can use the first two powers of his Primary power set and the first power of his Secondary power set. There is a stacking damage bonus for any attacks used from either set the effectiveness of which varies per power.
Defiance damage bonuses follow these formulas:
Duration = 7.5 + Activation Time
In other words, each bonus starts when an attack begins to activate and lasts throughout the activation, plus 7.5 seconds more. So every attack provides the exact same length of time for additional attacks to get its bonus.
Damage Bonus = 6.6% * Activation Time / Area Modifier where Area Modifier = 1 + (0.15 * radius) - ( 0.0003667 * radius * (360 - arc) )
So powers with long activations give bigger Defiance bonuses than quick ones do, and single-target attacks give bigger bonuses than small AoEs, which give bigger bonuses than large AoEs.
(Notice that Area Modifier is always just 1 for single-target powers and always 1 + (0.15 * radius) for circular AoEs. You only need the whole formula for cones.)
Original Defiance
This section contains information that no longer applies to the current version of City of Heroes. It is provided for historical purposes.
Defiance was changed to its current state on December 11, 2007. The previous version, introduced in Issue 5, made use of the "brown bar" on the UI, which represented a buff to Damage and ToHit. As a Blaster's HP dropped, Defiance's buff would rise. The exact mathematical forumlas used to calculate new Damage and ToHit values are as follows:
Multiplier = 2 ^ ((45 - HealthPercentage) / 10) DamageBoost = 25% * Multiplier ToHitBoost = 1.25% * Multiplier
Following that route, the buff values at 25% health would yield a 100% boost to Damage and a 5% boost to ToHit. At 5% health, there would be a 400% boost to Damage and a 20% boost to ToHit.