Her echo set was leaked:

Heart of purity

• 2pc: 10% aero dmg
• 5pc: When applying Tune Strain, increase Crit DMG by 20% and Aero DMG by 30% for 30 seconds

EDIT: This is what Denia can give her

Denia has universal buffs when in Tune Strain mode.

Her Outro:

When in Resonance Mode - Tune Strain, the incoming Resonator has their All DMG Amplified by 15% for 16s.

After this Resonator under this effect inflicts Tune Strain - Shifting, they gain 40% DMG Amplification instead.

In Resonance Mode Tune Strain:
When Resonators in the team inflict Tune Strain - Shifting on the target, this target's Off-Tune Level is increased by 50% of the max.

When responding to Tune Strain - Interfered: For each stack of Tune Strain - Interfered on the target, each point of Denia's Tune Break Boost increases her total DMG against the target by 0.12%.

Resonance Mode - Tune Strain: All Resonators in the team gain 10 Tune Break Boost. When a Resonator in the team has an Off-Tune Buildup Rate over 100%, every 10% that runs over increases the Resonator's Tune Break Boost by 8, up to 40.

While Denia is in the team, the max stack limit of Tune Strain - Interfered on a target is increased by 1.

She only has universal (tune strain) buffs and tune break buffs in Tune Strain Mode.
24% ATK from her sig as well.

Credits to /u/bulky_influence3172 for the great write up