Damage calculation

Damage Types
There are several different types of damage in Guild Wars.
 * Elemental damage
 * Fire damage
 * Cold damage
 * Lightning damage
 * Earth damage
 * Physical damage
 * Blunt damage
 * Piercing damage
 * Slashing damage
 * Other damage:
 * Holy damage
 * Light damage
 * Shadow damage
 * Dark damage
 * Chaos damage

Health Degeneration also causes loss of hit points, but isn't considered damage by the game engine.

Damage Calculation
To determine how much damage any attack or skill does, check the following:
 * Does its damage type get changed? (Winter, etc.)
 * Is the attack blocked or evaded?
 * Is the amount of damage modified? (depending on damage type and character's level)?
 * Does it ignore Armor?
 * Calculate resulting Damage with Armor and armor penetration:

[Source]
 * Base Damage is just a simple number. Two weak attacks always equal one attack that is twice as strong.
 * Weaker Armor (depending on damage type) is exponentially worse than stronger armor.
 * Armor penetration reduces the enemies armor.

Damage Groups
It is useful to classify damage into damage groups (especially for PvP).
 * Spike Damage
 * Damage Over Time