When crafting a Cold Affinity build in Path of Exile 2, the Passive Skill Tree and Ascendancy choices are critical to Path of Exile 2 Currency optimizing your build for maximum cold damage, freeze chance, and defensive capabilities. Cold Affinity specializes in slowing enemies, applying chill and freeze, and dealing significant damage over time (DoT) effects. Let's break down the best Passive Skill Tree nodes and Ascendancy classes for a Cold Affinity-focused build:

1. Key Passive Nodes for Cold Affinity Builds
When building a Cold Affinity character, you should focus on cold damage, freeze duration, chill effects, and damage over time nodes. These will maximize the effectiveness of your cold-based spells and skills while enhancing your ability to control enemies with freezing and chilling effects.

Cold Damage Nodes:
Cold Damage: Boosts cold damage for all of your cold-based skills (e.g., Frostbolt, Vortex, Ice Spear).

Elemental Damage: As cold damage is part of the elemental damage category, nodes that increase elemental damage will work well for cold builds, particularly in hybrid elemental builds.

Cold Penetration: Increases your ability to penetrate cold resistance, making your cold damage more effective against tougher enemies and bosses.

Critical Strike Chance & Multiplier: Cold builds often use critical strikes to apply freeze more reliably, so increasing critical strike chance and cold-specific crit damage can significantly enhance your cold-based output.

Freeze and Chill Effects:
Freeze Chance: Increases your chances of freezing enemies with cold-based attacks or skills. This is crucial if you want to make use of freeze-locking strategies in both PvE and PvP.

Chill Duration: Increases the time enemies remain chilled, which can make it easier to keep enemies slowed down for a longer duration.

Freeze Duration: Similarly, increasing the freeze duration allows you to freeze enemies for a longer time, ensuring they are incapacitated for extended periods.

Damage Over Time (DoT) Nodes:
Cold DoT: Many cold skills (e.g., Vortex, Ice Cascade) apply damage over time, so increasing cold DoT will enhance the sustained damage of your cold-based abilities.

Damage Over Time (DoT) Multiplier: Boosts all damage over time effects, which is especially important for Vortex, Icicle Barrage, and other DoT skills.

Defensive Nodes:
Cold Resistance: Helps you increase cold resistance, which is especially useful when fighting other cold-based enemies or bosses that deal high cold damage.

Energy Shield & Life: If you are aiming for a defensive cold build, you may want to focus on Energy Shield or Life nodes to bolster your survivability, especially when engaging tough bosses or high-damage enemies.

Movement Speed: Although not strictly cold-related, movement speed can be useful for evading enemies while maintaining freeze-locks on them.

2. Ascendancy Classes for Cold Affinity Builds
Ascendancies in Path of Exile 2 enhance specific aspects of your build. For a Cold Affinity build, you'll want an Ascendancy that supports cold damage, freeze effects, or damage over time. Here's a breakdown of the best Ascendancies to consider for a Cold Affinity-focused build:

Elementalist:
Best for Cold Affinity Builds: The Elementalist is the best Ascendancy for cold-based builds, providing several powerful passives that boost elemental damage, freeze effects, and cold DoT.

Elemental Overload: Increases elemental damage significantly after you use a skill that hits an enemy, perfect for cold skills that rely on freezing and chilling.

Shaper of Flames: Increases fire damage, but also grants elemental resistances, which can benefit cold builds. This passive can also improve the synergy with hybrid cold/fire builds.

Paragon of Calamity: This passive increases area of effect and elemental resistance penetration, which works well for cold skills like Vortex that cover large areas and require cold penetration.

Elementalist also has synergy with multiple elemental damage types, allowing for hybrid builds (cold and fire, cold and lightning, etc.), making it a great choice for maximizing cold damage alongside other elemental effects.

Occultist:
Best for Cold DoT Builds: The Occultist Ascendancy is ideal for cold damage over time (DoT) builds, enhancing your chill and freeze effects while focusing on damage over time.

Forbidden Power: Occultist's Forbidden Power increases your cold DoT and freeze chance, especially when combined with Vortex or other DoT-based cold skills. This passive enhances both defensive and offensive capabilities, allowing you to sustain long-duration damage while freezing enemies.

Profane Bloom: The Profane Bloom mechanic makes it easier to apply freeze effects on enemies and explode frozen enemies, dealing massive AoE cold damage.

Malediction: If you are playing a hybrid cold/chaos build, Malediction can increase your overall damage potential by amplifying your chaos and cold effects simultaneously.

Occultist is perfect for damage-over-time builds and players who focus on buy POE 2 Currency sustained cold damage rather than burst damage.