Astral Aegis (Patreon)

Armor (shield), legendary (requires attunement)

This dark shield reflects an ever-present starry sky. When observed at an angle, it looks as though you could reach through its glossy surface. While holding the shield, you have immunity to radiant damage and gain a +2 bonus to your AC. This bonus is in addition to the shield's normal bonus to AC. The shield has the following properties, which you can use while you hold it.

Astral Defender. When a friendly creature within 30 feet of you takes radiant damage from a hostile source, you can use your reaction to magically swap places with that creature, teleporting you both, provided the other creature is willing. You then take the triggering damage, instead of the other creature, unless that creature would still be affected by the triggering effect in its new location.

Astral Projection. You can use an action to cast the astral projection spell from the shield, without any material components. When the spell ends, this property of the shield can't be used again until 7 days have passed. If your silvery cord is severed, the shield is shunted into the Astral Plane and lost, but you and your companions are harmlessly returned to your bodies.

Astral Ward. You can perform a special ritual with the shield over the course of 1 hour, which can be done during a short rest. At the end of that time, a glimmering ward appears, centered on your location, which extends from you in a cylinder that's 100 feet tall with a radius of 50 feet. The ward remains at that location for 24 hours or until you leave the area. For the duration, creatures can't move or travel within the space using teleportation (except by the shield's Astral Defender property) or by extradimensional or interplanar means. In addition, when an aberration enters the ward's area for the first time on a turn or starts its turn there, it must succeed on a DC 17 Wisdom saving throw or take 5d10 radiant damage. Once a creature succeeds on the saving throw, it's immune to the effect for 24 hours.

Starlight protect you.

—Polaris farewell.