Boon of the Dragon Slayer (5e Epic Boon)

You gain the following benefits:

Any weapon you wield gains the properties of a dragon slayer as long as you are holding it.
When you are subjected to a breath weapon, you have advantage on all saving throws made against it and you cannot be reduced to 0 hit points or rendered unconscious by it.
When you are subjected to a dragon's Frightful Presence, you may use your reaction to succeed on the saving throw and cause the dragon to become frightened for 1 minute instead. The dragon can make a Wisdom saving throw (DC 8 + twice your proficiency bonus) at the end of each of its turns, ending the effect on a success.