The jar lift
Eventually, you’ll find yourself in an area shown in the image above. A jar lift takes you all the way down to a bridge leading to the boss’ chamber. Ride the lift but don’t jump down. Instead, look behind you to see a floor plate.
Step on this plate and get back on the lift. It will ascend all the way to the top. There, you’ll find the Elden Ring: Shadow of the Erdtree Night Armor–it’s actually a full set that includes the Helm of Night, Armor of Night, Gauntlet of Night, and Greaves of Night.
Furthermore, if you go up the steps and through the tunnel, you’ll also acquire the Shield of Night. The Shield of Night has the Revenge of the Night ash of war skill, which causes it to spew shadowy projectiles.