After two weeks of teasers, Grinding Gear Games has finally released the full details on Path of Exile's first mini-expansion, Sacrifice of the Vaal, along with the official trailer. As we already knew, Sacrifice of the Vaal revolves around Atziri, Queen of the Vaal. She has risen from the grave after two thousand years and now seeks to corrupt the land of Wraeclast to restore her beauty. Unsurprisingly, Queen Atziri will be the final boss encounter in the game, designed for high-level characters. "In order to gain access to Atziri's lair, you must collect fragments from Vaal-influenced areas throughout Wraeclast," which are then combined to create "six portals to the Apex of Sacrifice." Queen Atziri will not be the only boss you face though – before you can even get to her, you'll have to fight through several other deadly bosses.
While defeating Queen Atziri is the ultimate goal, there's a lot more to Sacrifice of the Vaal, with its content "layered throughout the entire Path of Exile experience." The way you acquire Vaal Fragments is by uncovering and conquering secrete corrupted areas, indicated by "a glowing, beating heart and swirling ribbons of blood." These corrupted areas are similar to end-game maps, so expect them to be rather difficult to take on without a friend. "At the heart of each corrupted area is a new boss monster, guarding a chest that is guaranteed to drop a Vaal Skill Gem or Vaal Fragment."
Vaal Skill Gems are essentially "the ultimate version of many contemporary Path of Exile skills." What sets them apart from normal skill gems aside from their devastating power, is that they're charged up by killing enemies. Some Vaal Skills will simply unleash all the power you've stored, while others can be used multiple times when fully charged. The other major new item introduced with Sacrifice of the Vaal is the Vaal Orb. Vaal Orbs allow you to intentionally corrupt your equipment, which "can yield unpredictable and powerful results." There are many possible outcomes and depends on the type of item, but the side effect is that it prevents the item from any further modification. "Corruption is currently the only way to obtain white sockets, certain implicit mods, gems with level or quality higher than 20, maps with eight mods, and various other exotic item states."
Along with the changes to the default game, two new Challenge Leagues are being introduced: Ambush and Invasion. Ambush is the Standard League and features strongboxes guarded by monsters that ambush the player when they are opened. In order to claim the strongbox's contents, all the ambushing monsters must be killed. Invasion is the Hardcore League and features monsters invading from other levels or acts. There will be "a unique boss monster from an invading monster type [...] lurking in each level, with powerful combinations of skills to catch the player off-guard." Since it's a Hardcore League, if you die, your character is "demoted" to a Standard character.
Due to all the unique monsters in the Invasion League, not to mention the secret Vaal-corrupted areas, over 60 new boss monsters will be added to Path of Exile when Sacrifice of the Vaal goes live. Grinding Gear has designed them to be especially lethal, featuring "advanced combinations of skills and support gems" that have never been seen in Path of Exile until now. For players that get tired of fighting AI, there will be a new long-term Cut-throat PvP mode, along with a free-for-all PvP area called The Sarn Arena.
The full patch notes for Sacrifice of the Vaal will be released on March 3, with the update going live at 1PM US Pacific Time on March 5. The first 50 players to defeat Atziri in each of the new challenge leagues will receive an exclusive cosmetic microtransaction effect.
Source: Official Site