Source: Bigby Presents - Glory of the Giants

Armor (Heavy), Very Rare (Requires Attunement)

Set in the center of this armor’s chest is a citrine engraved with the shield rune.

While wearing this armor, your hit point maximum increases by an amount equal to 10 + your level.

Invoking the Rune. As an action, you can invoke the armor’s rune to cast the Beacon of Hope spell with it; the spell has a duration of 1 minute and doesn’t require concentration. Once the rune has been invoked, it can’t be invoked again until the next dawn.