Aria Echo

Harmonic Invisibility. As a bonus action, the Echo flickers out of the audible frequency. It magically becomes invisible until it attacks, uses its Resonant Pulse, or until its [Tooltip Not Found] ends (as if concentrating on a spell).

Ephemeral.  The Echo can't manipulate or wear any objects. It can move through other creatures and objects as if they were difficult terrain. It takes 5 ([damage]1d10[/damage]) [damage]force[/damage] damage if it ends its turn inside an object.

Shock. Melee Attack Roll: +4 to hit, reach 5 ft., one creature. Hit: 9 ([damage]2d8[/damage]) [damage]psychic[/damage] damage. 

Consume Resonance.The Echo targets one creature it can see within 5 feet of it that has 0 hit points and is still alive. The target must succeed on a DC 10 Constitution saving throw or die. If the target dies, the Echo regains 10 ([damage]3d6[/damage]) hit points and the Harmonized Everlasting One gains Advantage on its next attack.

Vanish. The wisp and its light have the Invisible condition until the wisp’s Concentration ends on this effect, which ends early immediately after the wisp makes an attack roll or uses Consume Life.