Thunderclap and Flash v.2

You are a glass cannon, strong but fairly meek. You are scared easily and prone to fainting. You are "frightened" if you:

• Witness an Ally lose more than half their total hit points
• Witness an Ally become unconscious
• Witness an Ally Die
• Are surprised
• See a creature at least one size larger than you
• Are affected by anything that would render you "frightened" (automatic fail on the saving throw)

If you are frightened, you faint and are rendered unconscious for one turn. After the turn, you awaken but must make a wisdom saving throw of at least 15 to not be "frightened" again.

While unconscious, you may choose to awaken with one hit point, in a heightened state. You are shrouded in an Aura of Lightning, and then make a dash action (based on your movement speed), followed by a melee attack as a bonus action. Your blade strikes with a type of speed and accuracy that is unparalleled. The melee attack ignores AC and legendary actions, and it has a base +20 bonus to the damage roll. You can choose to increase the potency of this ability by "Six-Fold". You can now make six dashes in total, gaining a +10 to the damage roll for every dash, for a +60 to the damage roll (not including the base damage bonus). This puts an enormous strain on your body though, and you are rendered unconscious yet again and must wait the duration of a long rest before awakening again.

The base damage roll's bonus increases to +40 at level 10 and +80 at level 20. This feat may also be used if the user is rendered unconscious by any other means.

As the user levels up, the drawbacks of the ability lessen over time. At level 5, you no longer get "frightened" when an ally goes unconscious, or when an ally loses half their hit points. At level 10, you are no longer frightened when you see a creature at least one size larger than you, or when you are surprised. Also at level 10, you gain the ability to use this feat at will without the need to be frightened/unconscious, but the total damage bonus is halved. At level 15 you no longer get frightened when you see an ally die. Also at level 15, when you use your feat while conscious, your damage roll is no longer halved and does the same damage as it would while you were "frightened" or unconscious. At level 20, you become immune to being frightened by spell or any other means. 

This feat may be used once per day without consequence. It can be used twice in one day, but the user's legs are rendered useless after the second use, and their movement speed is decreased to zero.