Bands of the Abyss

These appear as two transparent bands with swirling black smoke inside, if you put your ear to them you can hear nightmarish screams. When you slide them onto each of your arms you immediately fall unconscious. The bands will dissolve into both of your arms as you remain asleep.  While in this nightmare, you must face four shadows in turn. Each one that you defeat, will emerge as a tattoo on your arms. Once you defeat all of the shadows or fall to them in combat, you will awaken from the nightmare and be attuned to the bands until death. You will gain 3 charges if you defeat all three shadows. Failure to defeat the shadows will not change the nature of these bands. You will simply suffer from nightmares.

Dark Form:

The tattoos regain all expended charges daily at dawn. As a bonus action while the tattoo is on your skin, you can expend 1 of the tattoo's charges to become incorporeal until the end of your next turn. For the duration, you gain the following benefits:

You have resistance to bludgeoning, piercing, and slashing damage from non-magical attacks.

You cannot be grappled or restrained.

You can move through creatures and solid objects as if they were difficult terrain. If you end your turn in a solid object, you take 1d10 force damage. If the effect ends while you are inside a solid object, you instead are shunted to the nearest unoccupied space, and you take 1d10 force damage for every 5 feet you must travel.

Nightmares:

Notes: Resistance: Bludgeoning, Piercing, and Slashing from Nonmagical Attacks, Immunity: Grappled, Immunity: Restrained