2. Energy Shield (ES) for Survivability & Scaling Chaos Damage
Energy Shield Buffer: For Chaos, Elemental, or Hybrid builds, Energy Shield provides a vital buffer against large hits, enabling you to absorb damage that would otherwise have taken your health pool. This makes it easier to POE currency focus on stacking Offensive Auras like Anger or Wrath (for Elemental builds) without worrying about your health pool.

ES Scaling with Damage: The Energy Shield layer also allows for scaling other forms of damage mitigation such as Chaos Resistance or Elemental Resistances, which increases your effective health pool and enables you to focus on damage uptime (since you are not forced to heal as frequently). When Life Leech or Energy Shield Leech is added to the mix, you can sustain offensive momentum through the ES layer while continually dishing out damage.
Chaos Damage Builds with ES: Chaos damage builds, in particular, can benefit from scaling Chaos Resistance, Energy Shield layers, and Leech to turn the defensive aspects into offensive synergy. Chaos damage over time or Essence Drain builds, for example, can continuously dish out damage while buy POE2 Currency using ES as a buffer. The extra health regeneration from Chaos Leech combined with high ES allows you to focus on high damage output without needing constant healing.