PoE 3.27 league is now live! While this update doesn't bring a huge amount of new content, fully exploring it will still take some time. Therefore, I guess you haven't unlocked Bloodline system yet, as it requires defeating the corresponding endgame boss.
If you have a general understanding of Keepers of the Flame league, you'll know that most of the league's new mechanics focus on adding usable buffs, such as Genesis Tree and Bloodlines.
As a holistic system, Bloodlines are also called Bloodline Ascendancy because they are similar to your secondary Ascendancy classes. There are currently 10 known Bloodlines.
Next, we'll explain how Bloodlines work and delve into the combat effects and acquisition methods of all 10 Bloodlines.
Bloodline System Overview
This system was added to Path of Exile after the release of Keepers of the Flame league. Each one must be unlocked by defeating the corresponding endgame boss or completing the relevant encounter.
The similarity between Bloodline Ascendancy and regular Ascendancy classes lies in the shared allocation of Ascendancy passive skill points. The difference is that Bloodline selection is not restricted by the base class, allowing for free choice and the ability to change it later.
After completing a related boss battle, an altar will appear nearby. Interacting with it unlocks the corresponding Bloodline. Interacting with new altars unlocks new Bloodlines and allows you to switch between them.
Because they share the same allocation points, you need to be more careful and strategic when allocating points for Bloodlines and regular Ascendancy classes. However, reallocating points is not difficult, as points can now be refunded or returned in gold.
1. Oshabi Bloodline
This Bloodline requires defeating Oshabi, the Avatar of the Grove, the final boss you encounter while exploring Harvest mechanic, provided you consume Sacred Blossom to summon him in the corresponding map.
To obtain this summoning item, you need to kill T4 enemies like Janaar, the Omen in Harvest Mechanic to get it as a drop. Then, enter The Sacred Grove and interact with a tree you encounter to meet Oshabi.
Originally, killing this boss would reward you with items, including PoE currency. After 3.27 league launch, you will also be able to get Oshabi Bloodline, a special power based on Azmeri magic, from the altars that appear.
2. Chaos Bloodline
The boss corresponding to this Bloodline is The Trialmaster, who only randomly appears in T14 and higher-level maps with a very low probability. If you want to unlock Chaos Bloodline, it's best to use Ultimatum Scarab of Duelling to increase its spawn rate.
Sometimes this boss will also appear as the ultimatum encounter boss in areas of level 81 and above, teleporting you to the arena for a duel. After defeating him, you will be able to master Vaal skills or corrupted powers through Chaos Bloodline.
3. Aul Bloodline - Primordial Knight
The corresponding boss, Aul the Crystal King (also known as Ahn), will randomly appear in Crystal King's Throne nodes of Primeval Ruins biome after you've explored more than 130 levels of Azurite Mine.
Generally, the boss's appearance frequency only becomes more stable after you've explored at least 200 levels of Azurite Mine, so obtaining Aul Bloodline is highly dependent on luck.
As for its effect, regardless of your base class, this Bloodline provides an opportunity to unlock a unique node, preventing your movement speed from being reduced.
4. Lycia Bloodline - Herald
This Bloodline is unlocked after defeating the boss Lycia, Herald of the Scourge. She is the boss of T17 Sanctuary map. You need to obtain Forbidden Tome by killing other normal enemies on the map before you can unlock her encounter.
The effect of Lycia Bloodline is that when equipped, it unlocks a Herald node, granting the power of elemental conversion and profane ground options.
5. Delirious Bloodline - Impostor
Unlocking Delirious Bloodline doesn't require defeating a specific boss, but rather completing enough Delirium encounters to obtain 300 Simulacrum Splinters to complete Simulacrum.
Generally, you need to complete at least 15 Delirium encounters to get enough Simulacrum Splinters. Unlocking Delirious Bloodline will increase your defense and attack power.
6. Olroth Bloodline - Runesmith
The corresponding boss, Olroth, Origin of the Fall, has a chance to appear in level 81+ logbooks while exploring Knights of the Sun site. The original loot included Olroth's Resolve, Cadigan's Crown, and Vorana's March.
Defeating him will now unlock the altar to obtain Olroth Bloodline, helping you improve or better utilize Ward's power.
7. Catarina Bloodline - Lich
First, you need to kill the leaders in Betrayal Safehouses in areas of level 78 or higher to obtain Syndicate Medallion, which may drop. Then, use this item to enter Mastermind's Lair to unlock Catarina encounter.
Catarina Bloodline grants summoning power, allowing you to summon additional minions for assistance. If your base or Ascendancy class is already summoning, you can choose this Bloodline to further enhance yourself.
8. Farrul Bloodline - Animist
As the easiest Bloodline to obtain, Farrul Bloodline's boss is Farrul, First of the Plains, located in Farrul's Den. You can unlock the portal to this location by Farric Tiger Alpha and any three yellow beasts.
Once you obtain Farrul Bloodline, you will unlock nodes that allow summons or spells to deal more damage, making it a Bloodline focused on damage enhancement.
9. Breachlord Bloodline
To obtain this Bloodline, you need to defeat both It That Was Tul and It That Was Esh. These two bosses usually appear simultaneously in Hive Colony added in 3.27 league.
10. Nameless Bloodline - Ritualist
This Bloodline currently lacks a specific name, perhaps because the corresponding boss, King In The Mists, is quite challenging and difficult to defeat quickly.
You need to clear enough Rituals to obtain the drop An Audience With The King, then use it in the map device to enter the boss arena, Crux of Nothingness.
More information about Bloodline corresponding to King In The Mists will likely be revealed as the league progresses further. For now, your task is to choose Bloodline that best suits your abilities from the first nine Bloodlines!
