Helm of Brilliance
While wearing this helm, you gain the following benefits:
* You can use an action to cast one of the following spells (save DC 18) with the listed gem as its component: _daylight_ (opal), __fireball_ (fire opal), _prismatic spray_ (diamond), or _wall of fire_ (ruby). The gem is then destroyed.
* If at least one diamond remains, the helm casts dim light in a 30-foot radius if at least one undead is within 30 feet. Any undead that starts its turn in the light takes 1d6 radiant damage.
* If at least one ruby remains, you have resistance to fire damage.
* If at least one fire opal remains, you can use an action to speak a command word and cause a weapon you are holding to erupt in flames, causing it to deal an extra 1d6 fire damage on a hit. The flames cast bright light in a 10-foot radius and dim light for an additional 10 feet. The flames last until you use a bonus action to speak the command word or you release the weapon.
* Whenever you fail a _saving throw_ against a spell and take fire damage as a result, roll a d20\. On a 1, light blazes from the remaining gems. Each creature within 60 feet other than you must succeed on a DC 17 Dexterity saving throw or take radiant damage equal to the number of gems in the helm. The helm and the remaining gems are then destroyed.