Game Mechanics
Master guide to POE2's elemental and status effect mechanics
Categories
Active skills come from Uncut Skill Gems, which drop at area level. You 'engrave' an Uncut Skill Gem to pick or upgrade a specific skill.
Support gems modify a linked skill. As of 0.3.0 the one-copy-per-character restriction was removed, and supports now carry tiers (for example Brink I/II) that set their stat ranges. Higher support tiers are gated by your Uncut Support Gem level (1, 2 or 3).
There is no '5-tier' support system: the number 5 is the socket limit - the maximum number of support gems you can link to a single skill. You add support sockets with Jeweller's Orbs (Lesser -> 3, Greater -> 4, Perfect -> 5 sockets).
Leveling grants passive skill points and access to higher-level gems and gear.
Each base class unlocks ascendancy specialisations through the Trial of the Sekhemas and the Trial of Chaos.
Equipment provides defensive and offensive stats plus rune sockets; runes add fixed stats such as resistances or life.