Backstab

A backstab is a type of critical hit, with prerequisites to perform.

Backstab vs Critical
The damage calculation for the critical hit and the backstab are identical; the primary difference between the two being that a critical hit has a percentage chance attached to every weapon (regardless of type, etc), whereas as a backstab requires a melee weapon (among other things). The specifics of this are discussed below.

Please also note that, while Backstabs do "critical damage", they are not considered by the game to be a "critical hit". The ramification of this is that a Backstab will not shatter a frozen or petrified target. Rogues wishing to do so, without using a talent, may wish to stealth and then use a bow. A hit will generate an automatic critical hit and shatter the target.

Implementation
The code below was found in Dragon Age scripts combat_h_nns, in relation to backstabbing with a bow/arrow. Combat_CheckBackstab is *only* called here: if (nAttackType == ATTACK_TYPE_MELEE) { // If we are backstabbing, we can change the result here if it was a crit. Abilities never bs (anim priority) if (nAbility == 0 && Combat_CheckBackstab (oAttacker, oTarget, oWeapon, fFlanking)) { nRet = COMBAT_RESULT_BACKSTAB; } } I have read through more of the code and to summarize this is how it works:


 * The damage effect of critical hits and backstabs are the same
 * If you hit then there is a percentage chance of critical hit (which is 100% if you are in stealth and make a flanking attack) This can happen with both melee and ranged weapons, but the chance is reduced beyond the ranged weapon's effective range.
 * Damage calculation is based only on the main-hand weapon
 * If you hit the the target and all of the following is true then a backstab will occur:
 * The attacker uses a melee weapon
 * The attack is a normal attack and no activated ability ( i.e. you cant backstab with deadly strike )
 * The attacker is a rogue
 * The attacker is humanoid
 * The target is not immune to critical hits
 * Dual Striking mode is not enabled
 * The attacker is flanking the enemy or the target is stunned/paralyzed and the attacker has Coup de Grace

In summary:

You can critically hit with a bow, but you cannot backstab with a bow.

You can backstab with any melee weapon, but you cannot backstab with staves, which can never critically hit either.