Penetration or PV is a stat that every weapon has. It is directly opposed by armor in the form of AV; each point of AV negates a point of PV.
The full details of how PV works are described below, but for a quick shorthand summary, every two points of additional PV raises the multiplier applied to the damage your weapon deals by one; conversely, every two points of AV the target has lowers it by one. When PV and AV are exactly equal, the weapon's damage multiplier will generally range from x1 to x3 - in other words, an AV of eight is sufficient to reduce most attacks from weaker enemies to no damage at all.
PV is based on the weapon's own penetration stats, and the player's Strength modifier. Before we start counting on the penetrations, this page also include information on accuracies. The general calculation used is the same as every other roguelike but with this one called penetration value which are unique to Qud
Lets first consider on the conditions first.
- Consider the Accuracy
- Every attack, regardless of weapon type, starts by rolling a number between 1 to 20
- Then add the Agility modifier value to the number; for this there are no limit on how much agility can affect the accuracy
- Then add once more, the "To-Hit" modifier to the number
- If sum of those values exceeds the target's DV then the attack will hit
- Essentially, making character with more than 20 DV is very viable dodge build
- Consider the Critical Hits
- If its a critical hit then you are guaranteed at least 1 hit, and also (for the player only) gains extra penetration value.
- Consider the Engagement of the Weapon
- Melee weapon receive bonuses from your strength modifier depending on their cap.
- Ranged weapon do not receive bonuses from strength modifier at all and they each have set amount of penetration value
- Consider the Elemental Damages
- There are various damage types in the game, and some weapon do deal special damages
- There are four known elemental damage type: Heat, Cold, Acid, and Electricity
- These value also consider the target's elemental resistance when dealing its final damage, but not before they calculate whether the weapon penetrate or not
- There are few more special damage type: Explosive, Vibrating, Mental and a couple more
- Explosive damage always ignores both the DV and AV, meaning it will deal the full extent of it's damage value to the target.
- Vibrating damage instead uses the target's AV as it's penetration value, as such they can never penetrate more than thrice (see why below)
- Mental damage, instead of using AV and DV to calculate its penetration, it instead uses MA which stands for "Mental Armor".
- There are also, Disintegration damage which not only it ignore penetrations like explosive damages, they also deal x10 as much damage against non-biological creatures such as robots.
- Light damage doesn't have any special penetration properties, they always hit their target regardless of accuracy but they can be reflected entirely by mutant with Light Manipulation skill.
- Laser weapon also counted as light damage and can be reflected by such
- Consider the Type of the Weapon
- Consider the Strength Modifier
- All penetration rolls begin with their current penetration value, plus the attacker's strength modifier.
- Your strength modifier is added directly to the weapon's starting penetration value, up to their strength bonus limit.
- Different weapon material has different limit to be affected by strength aside from the hp damage.
- Bronze weapon only benefits to (+1) Strength modifier while Zetachrome weapon benefits up to (+9) Strength modifier.
- Your fist and any other unarmed fist weapons has no strength bonus limit and will benefit for as much as it could go for.
- If your strength modifier is actually below its required value, such as (-1) then the weapon penetration will be reduced straight for that amount.
- Consider weapon modifiers
- Simply to put, any weapon with Sharp modifier receives another flat +1 bonus to its penetration.
- Consider any other Skill Bonuses
- Some weapon passive skill tend to add more penetration to the calculation such as for the aggressive stance from Long Sword skill tree which adds a penetration value of +1 or +2.
- The charge active skill always add another penetration when calculated.
Now let's calculate how much it would hit. Listen to the conditions first.
- Your character (the attacker) has a Iron Long Sword and he also has 22 STR and 20 AGI
- You are actively using the charge skill which adds a penetration value
- Your target (the defender) has a DV value of 10 and the AV value of 3
Now lets calculate the penetration value
- Since the Iron Long Sword is a long blade weapon category, you would receive a starting penetration of: +4
- But you also have 22 STR Value which adds to the modifier of (+3). Your Iron long sword however can only benefit up to 2 strength modifier bonus so it only adds the total to +2
- Therefore the total penetration value of it would be ->6
Now lets see your attack
- First you made an accuracy roll, you rolled a number between 1 to 20 and rolled a 9, since you have the 20 AGI with bonus modifier of (+2) your accuracy roll becomes 11, so your attack would hit because 11 is higher than your opponent's DV which is 10.
- Now you rolled your first set of penetration checks. These penetration checks require rolls between -1 and 8 (1d10-2) to which you add your penetration value and come in sets of 3. These checks are then compared to your opponent's AV. Since your opponent's AV is 3 in this example, every roll totaling 4 or more will hit
- For your first set of penetration checks, you rolled 6, 7, and 5 to which your penetration was added to get 12, 13, and 11. Since at least one of these succeeded, you got to roll the damage die for your weapon once.
- Additionally, because all three of the penetration rolls were successful, you get to make another set of penetration checks but with a -2, a process that will repeat with each subsequent set of penetration checks adding another -2 penetration penalty (-2 at second set, -4 at third set, etc.)
- As such, you make a second set of penetration checks. For this set of rolls, you rolled 8, -1, and 7 to get totals of 12, 3, and 11. While you got 2 successes making this a successful set of checks, you failed to get 3 and thus move on to the damage roll.
- Finally you made the damage roll: an Iron long sword has the damage roll of 1d4, meaning it would have to roll 1 4-sided dice. However, because you had 2 successful checks, you multiplied the number of dice to get 2d4 for your damage roll instead. Because of that, you were able to roll a total of 7 damage.
- Caves of Qud will depict this in the message log as "You hit (x2) for 7 damage with your iron long sword! ."
Probabilities of different penetration multipliersEdit
As detailed above, the chance of penetrating and getting a higher penetration multiplier (x2, x3, x4 etc.) purely depends on the difference between the weapon's PV and the target's AV. If PV-AV is -8 or less, you cannot normally penetrate at all and must depend on critical hits. If PV-AV is 2, you are guaranteed to hit at least x1, and up to x5. For each 2 points of PV over AV+2, you get one more guaranteed hit, so at PV=AV+10 you will hit at least x5.
Here's the calculated chances to hit a specific number of times with given PV-AV, assuming no critical hits:
For higher PV: if PV-AV=2n, use the "0" column and add n guaranteed hits. If PV-AV=2n+1, use the "1" column and similarly add n hits.