The Resonance Chain in Wuthering Waves allows your Resonators to go above and beyond. You can basically stack duplicates of the characters to unlock Sequence Nodes that provide powerful passives. For versatile sub-DPS like Iuno, the Resonance Chain grants additional stacks, damage bonuses, and other special effects.

This article further discusses Iuno's Resonance Chain in WuWa.

The Resonance Chain for Iuno in Wuthering Waves unlocks the following passive at the respective Sequence Node:

Also read: Best teams for Iuno in Wuthering Waves

Iuno is a versatile sub-DPS with different support capabilities and doesn't require much of an upgrade to be effective in battle. Hence, we recommend skipping her Resonance Chain completely. You can instead use the resource to get her signature weapon, which buffs her damage.

That said, if you have saved up Astrites specifically for Iuno, her Sequence Node 2 is a big upgrade. It offers a massive damage boost to the overall team with the 10 stacks of Blessing of the Wan Light. Iuno's Sequence Node 3 is another potent upgrade to have, as it boosts her personal combat potential.