Path of Exile: Siege of the Atlas Features

Grinding Gear Games today unveiled the promised details about Siege of the Atlas, a new expansion coming next month to Path of Exile, the free-to-play action/RPG. This includes a new Official Trailer with a look at what to expect. Here's a handy list of what's to come:
Siege of the Atlas Content and Features:

  • Updated Atlas: The end-game Atlas of Worlds has been simultaneously simplified and also made deeper. The region system has been removed, and individual Atlas Passive Trees have been replaced by one gigantic Atlas-wide passive tree which creates a more flexible way for players to engage in the content they like best while also increasing its challenge and reward.
  • Four Pinnacle Bosses: The new storyline is capped with four new Pinnacle Bosses, ultimate boss fights for players seeking additional challenges. These bosses can potentially drop a selection of extremely valuable new unique items.
  • Endgame Item Crafting: Players can master the Eldritch Implicit Modifier system to improve their best items. New currency items allow them to craft powerful new implicit modifiers onto items that enable new build opportunities.
  • Archnemesis League: Players can collect modifiers to use on Petrified Monsters that are encountered throughout Wraeclast in order to create their own mini-boss fights. Each modifier provides a reward and a monster behavior and will stack in subsequent fights to create progressively more dangerous and rewarding encounters. These modifiers can be combined to create recipes for even more challenge and reward.
  • Game Balance Improvements: Spellcasters and Archers have been targeted with a massive selection of balance buffs, so that they are even more competitive with Path of Exile's best builds.