C1 - Primarily good for the increased damage it grants her Normal Attacks, being a 20%+ increase to her Normal Attack damage. The interruption resistance can be helpful when playing her without a shield, but does not alleviate her fragility.
C2 - Removes the need to wait for setup, as Blood-Debt Directives will be Due when applied. Increases Arlecchino’s frontload potential by granting her an AoE nuke when she absorbs these Dues, and further increases all her damage resistance by another 20% when this is triggered.
C3 - As Arlecchino’s primary damage comes from her Normal Attacks, this Constellation offers a significant damage increase.
C4 - Makes it easier to use Arlecchino’s Elemental Burst every rotation, the Cooldown Reduction is not particularly impactful however.
C5 - Elemental Burst levels only increase the damage it does, not very significant overall, but works well with her final Constellation.
C6 - Increases Arlecchino’s Elemental Burst damage by a massive amount based on her current amount of Bond of Life, making it worth using purely for damage.
Note that as this is scaling based on her current Bond of Life care should be taken not to use it at the end of a rotation when her Bond of Life has been depleted, instead it can often be ideal to use it immediately after her Elemental Skill to absorb the newly applied Dues which also resets her Elemental Skill to allow her to use it again if anything is still alive.
Also grants a significant CRIT Rate and CRIT Damage increase after using her Elemental Skill. Overall an extremely potent buff, befitting of a capstone Constellation.