Skills
Skill Types
There are two types of skills: spells, and attack skills. Skills that use weapon damage are attack skills. Everything else is a spell skill.
Attack skills – Effected by your weapon’s DPS. Attack speed, accuracy, and bonus damage from gear(ex. 1-7 lightning damage on a ring) are applied to attack skills.
Spells – Spells are not effected by weapon DPS. Percent cast speed, percent elemental damage(cold, fire, lightning), percent spell damage, and critical strikes effect the damage output of your spells. Bonuses such as 1-7 lightning damage on gear does not factor into your spell’s damage.
Support Gems
Support gems work very intuitively. For example a skill that causes direct damage but has no area of effect will not benefit from a support gem which increases the area of effect of skills. Similarly a skill which has no damage component will not benefit from a support gem that adds lightning damage.
Gem Quality
Gems can have quality bonuses just like items and flasks. The quality of a gem can be improved by using a Gem Cutter’s Prism. Gems with +% quality also drop from mobs and can be very valuable(so pick them up!). Here’s an informative spreadsheet detailing the bonuses given by increased gem quality to every skill gem available. The quality of a gem has dramatic impacts on the skill’s effectiveness and this should not be overlooked as a path to upgrading your character. For example a Lightning Strike gem with +16% quality will increase the physical damage % of Lightning Strike by 43% more, compared to a gem with +2% quality which increases the physical damage % by only 3%. Increase the quality of your primary gems whenever possible.
Skill gem experience gain
- Gems gain experience equal to 10% of the experience you gain.
- Gem experience is independent of the number of gems equipped. Your skill gems will level up at the same rate whether you have two skill gems equipped or twenty.
- Gems do not lose experience when you die.
Flasks
There are four types of flasks: Life, Mana, Hybrid, and Utility.
Life, Mana, and Hybrid flasks
When used(by hitting the 1-5 number keys) these flasks grant you life or mana regeneration. How much life or mana you recover is denoted by the Life Recovery and Mana Recovery labels. Hitting maximum life or mana before the full effect of the flask has been used will cause the life or mana regeneration effect to stop prematurely.
For example: you are at 100/300 life, and 150/200 mana. You use a hybrid flask that has 400 Life Recovery, 200 Mana Recovery, and Recovery Time of 8 seconds. After 2 seconds, you will be at 200/300 life, and 200/200 mana, and the mana recovery effects ends. The life recovery continues, and at 4 seconds, you have reached maximum life, and the life recovery effect also ends.
Flasks can have magic modifiers that provide bonuses while the flask effect is active, for example increased movement speed or resistances. These bonuses end when the life/mana recovery effect ends.
When multiple flasks are activated the effects are queued and not cumulative. For example if you drink two health flasks they will not grant double health regeneration. Rather the flask with the highest health/second effect will take effect first and when that effect runs out the regeneration effect from your second health flask will kick in.
Utility Flasks
These flasks give a temporary bonus for a set duration. Unlike the other flasks, the effects are not queued, each effect has its own timer that can overlap with other effects. The default effects of the flasks will not stack. For example:
The default effect of a Granite Flask grants you +4000 armor. You can find magical Granite Flasks with more properties, such as +25% movement speed. If you drink a regular Granite Flask you will gain +4000 armor. If you drink another Granite Flask with a 25% move-speed mod while your regular flask is still active you will gain the +25% move speed but not an extra +4000 armor.
Flask Charges
Drinking a flask consumes flask charges. Mouse over a flask to see how many charges it uses per use and the maximum number of charges that it holds. When you or a minion(totem, zombie, trap, etc.) kills an enemy ALL of your flasks gain charge.
Normal mobs grant one charge. Blue monsters grant three to five charges each. Yellow mobs grant six charges each.
If you had three flasks with 20/40 charges and you killed a yellow mob all three of the flasks would gain six charges and be sitting at 26/40.
Attributes
Life and Mana per level
Each time you level your character gains +6 life, +4 mana, and +3 evasion. This is the same for all character classes.
Attributes
Your attributes determine what skills and equipment you can use. They also grant passive bonuses:
Strength grants +0.5 life and +0.2% melee physical damage per point
Dexterity grants +2 accuracy and +0.2% evasion per point
Intelligence grants +0.5 mana and +0.2% energy shield per point
10 Strength grants: +5 life, +2% melee physical damage
10 Dexterity grants: +20 accuracy, +2% evasion
10 Intelligence grants: +5 mana, +2% energy shield
Life and mana regeneration
All classes have a base mana regeneration rate of 105% of their maximum mana per minute. “Increased Mana regeneration rate” modifies the base mana regen rate. For example, 20% Increased Mana regeneration rate would result in 105 * 1.2 = 126% per minute.
All classes start with zero life regeneration. Life regeneration can be gained through the passive skill tree and as modifiers on items.
Life gained from life leech is capped at 20% of your maximum life per second. Ex. you 1000 maximum life and leech 600 life with a single attack. The 20% cap says you can only gain 200 max life per second so it takes you three seconds to regain the life you leeched with that single attack. Like flasks the life regen provided by life leech ends when you reach full health.
Mana regained from mana leech is capped at 12.5% of your maximum mana pool per second.
Credit goes to poster Malice who compiled most of this information on the PoE forums here.