Incorporeal Movement. The echo can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object. Inspired. The following numbers increase by 1 when your proficiency bonus increases by 1: the echo's AC, its skill bonuses, and the bonuses to hit and damage of its Necrotic Touch.
Necrotic Touch. Melee Weapon Attack: +4 to hit, reach 5ft., one target. Hit: 4 (1d6 + 2) necrotic damage.