The game is out, so I'm free to answer questions and talk about the game
I'll use this first post to try and clear up some questions I've seen asked several times that didn't already get a clear answer. Hopefully these will help. If you have others, just ask. No guarantees I'll know the answer though!
I'm sticking this in the spoiler forum, since there's no explicit spoiler tag, and some of this material may touch on stuff people don't want to know just yet. You have been warned!
I'll update these posts as questions are asked and answered, or if information is corrected by the devs.
Visit this page for all your skill calculation needs:
http://www.titancalc.com/
Attributes
In most cases, attributes that boost damage affect any source of that damage, weapon, staff, bow, many skills, etc. Attributes do NOT boost +flat modifiers from equipment or skills. Str does not boost the Physical damage from Earth or Dream, nor does Dex help the piercing damage from Scatter Shot. Int DOES help Elemental spell damage.
Strength:
Increases Physical damage dealt. At lower levels, the absolute bonus generally gives you a larger boost, particularly with attack speed modifying items, later in the game, the percentage boost can become very substantial, especially in concert with other damage modifying items. Because of the absorption property of armor,
some physical damage can always get through armor (more on this below)
PHP Code:
(physicalDamageDV*((strengthDV/500)+1))+(strengthDV*0.04)
Each 50 points of Strength adds 10% Physical damage and +2 flat Physical damage.
Dexterity:
Increases Piercing damage dealt. Dexterity gives a slightly smaller bonus per stat point than strength, but remember that Piercing damage completely ignores armor. Keep in mind that some enemies are Pierce resistant (particularly skeletons, who are very common Undead enemies)
Because most weapons deal a fairly small percentage of piercing damage, focusing heavily on Dexterity for damage is probably not wise
unless you are using a Mastery that gives bonus Piercing damage - either Hunting or Rogue can add 50%+ Piercing damage easily. This means that Warfare/Rogue for dual wielding piercing swords, or Hunting/Warfare for Spears, or Hunting/Rogue are all 'obvious' natural combinations for heavy Pierce damage.
Dexterity also adds to OA/DA. If you are focusing specifically on offense or defense, items that directly increases OA/DA directly are going to give you more punch per point than Dexterity, but Dexterity gives both and boosts your Piercing damage. In any case, increased OA gives you a chance for critical hits
and increases the potential severity of those critical hits. You need to have an OA much higher than your targets DA to score maximal (50% added) critical hits. Note that crits only apply to melee hits, and only boost the physical and pierce damage dealt. DA works in reverse, decreasing the chance for opponents to hit you, damage you, and crit you.
PHP Code:
(pierceDamageDV * ((dexterityDV/1000)+1))+(dexterityDV*0.03)
Each 100 points of Dexterity adds 10% Piercing damage and roughly +1.95 flat Piercing damage
Note that Dexterity was changed from 65 points per 10% in TQ to 100 points per 10% in IT
Intelligence:
Increases Elemental damage dealt. Also increases Elemental damage over time. Elemental damage is Fire, Cold, Lightning, and Frostburn/Burn. Note that there is an entirely separate damage type (and resistance) known as 'Elemental' damage (literally, just flat Elemental damage). This damage type is very rare however, only a few items give it as a damage bonus. A few items do give explicit resistance to it, and in the case of resistance, it DOES add to normal Elemental resistances.
Armor has no effect on Elemental damage, only resistances help against it. To the best of my knowledge, there are no immune monsters to ANY basic damage type (Elemental/Physical/Pierce) anywhere in the game, though there ARE creatures with very high resists to specific damage types.
Intelligence also increases base Energy regen, and allows you to wear 'Mage' class armor, necessary if you're going to get a high Energy regen rate later in the game, as all Mage armor comes with built in +% Energy regen mods - note that this is only really necessary for characters that depend on Energy to deal damage. Most hybrid characters can get by with Energy potion usage.
Because increasing your Elemental damage output requires a fairly heavy investment in Intelligence, you need to consider if it is worth investing in for as a Hybrid character. You may get a better return on investment from Strength (flat physical) or Dex (flat Piercing PLUS OA/DA bonuses). However, it is worth noting that point for point, Piercing OR Elemental are likely to deal more damage to most creatures than Physical is (in most cases).
PHP Code:
(elementalDamageDV * ((intelligenceDV / 650) + 1)) + (intelligenceDV*0.025)
Each 65 points of Intelligence adds 10% Elemental damage, and roughly 1.625 flat Elemental damage (I'm not certain how far out TQ keeps the decimal)
PHP Code:
elementalDamageDV * ((intelligenceDV / 500) + 1)
Each 50 points of Intelligence adds 10% to Elemental duration damage, spread evenly over the duration (yes, you get a bigger bonus to Burn/Frostburn/Electrical Burn!)
Combat Details
Face smashing, ancient Greek style
Ok so, how do weapons actually interact with armor?
Well first off, when you get hit by a monster, a location on your character is randomly chosen, weighted between the various spots on your body. 40% of hits go to your chest armor. Each other body spot has a 20% chance to be hit. Yes, this means that walking around with low armor in one body spot can occasionally result in hard hits.
Next, any physical damage taken
up to the armor value of your armor is reduced. Mastery skills that add bonus armor add it to ALL locations (handy). Any damage in excess of the armor value in a given location is taken fully by your character.
Here's the part that isn't at all immediately apparent: Physical damage reduced by armor is reduced by 66%. That's right, armor does NOT fully soak damage. Also, Pierce damage completely ignores armor.
This property is known as 'Armor Absorption', and if you check the skill trees, you'll notice that several skills can boost this 66% Armor Absorption value, greatly increasing the power of equipped armor (Defense, of course, has a tier 1 skill that can raise this modifier).
Think of armor as 'physical resistance', in the same way that resists lower but do not fully eliminate non physical damage (indeed, all resists are capped at 80% in any case), armor can soften damage taken, but not eliminate it fully.
Stonewalling
However, there is one last line of defense against physical attacks, and that is a shield.
Shields are highly potent defensive tools, because a) they can block both melee and ranged attacks and b) they block their soak amount FULLY. This makes shields very powerful defensive tools.
All shields have a 'recast' block timer of 3 seconds, before other modifiers
Shields do have a cooldown time before they can block another attack, preventing you from sponging up every attack that comes your way (though Defense, again, has a modifier that can reduce this shield block time, and there is a Charm that can help here too).
Additionally, Shield damage reduction is done AFTER resists are taken into account (in other words, it's highly likely that if you have high armor/pierce resistance, the shield is going to stop the hit completely)
Couldn't hit a Cyclops in a barrel
These notes about OA ONLY apply to melee! Ranged attacks and staff attacks always hit, never crit. DA works for anyone against melee critters of course.
This info is dated, see below in the last post for a link to a table with precise OA/DA calculations
The way OA and DA compare, with even values, you have a 100% chance of hitting your target. The scale is very soft, so missing is rarely an issue. Of greater interest is the critical calculations. Consider this information suspect, since I don't have direct verification :P
Going by the equations in the database, each 100 points of OA over your target's DA gives you a chance to hit the next 10% tier of critical hits. That is, if your OA is 150 and your targets is 50, you have a chance of scoring a 110% hit. 250/50, 120% hit, and so on. Note that these crits cap out at 150% damage.
You can't see these values in the game (though medierra indicated he was looking at adding a display that compared your OA to the last target's DA that you hit, which would make this much easier to calculate), so the only way to get a feel for how your OA is doing relative to your opponents DA is to watch the critical hits (make sure to turn on the critical hit display in the options menu).
If you are scoring frequent critical hits, your Dex + your OA bonuses are probably sufficient. Conversely, if you are seeing frequent red numbers, you should think about raising either your Dex, or getting gear with +DA modifiers. Note that some enemies (say, Zombies) have lower DA than normal - generally big slow targets do. On the other hand, fast vicious enemies (say, Mantids) often have comparatively high OA, resulting in more critical hits.
In any case, since you can't see the numbers directly, it's best to simply decide if you want to focus on OA or DA, and skew your gear (and possibly your attributes) in that direction. If it would be beneficial to your character based on your Mastery selections, focus on OA or DA, otherwise you may not need to worry about them (beyond enough DA to avoid constant crushing critical hits in the higher difficulty levels)