Disclaimer: This feat is designed to enable one player character to effectively play published D&D adventures that are designed for a whole party. It is completely overpowered for use in a game with multiple players in it so should never be used as such!

 A character with this feat gains the following benefits:

Action Economy

• The character gains 3 Legendary Actions at the end of each of their turns. These actions can be used to take any Action or Bonus Action at the end of another creature's turn,  the character can use any unused Legendary Actions at the start of their turn.
• The character ignores the "Casting Spells as a bonus action" rule.
• The character can concentrate on two spells at the same time, if they take damage they roll a separate concentration check for each one.
• When the character is reduced to 0 hit points they do not become unconscious, instead all spells they are concentrating on immediately end and they fall prone and cannot stand up and cannot use Legendary Actions until they regain at least 1 hit point.
• The character can use 1 reaction on each creature's turn.

Defenses

• +15 hit points per level
• +2 bonus to AC
• Proficiency in all saving throws
• If the character ends their turn with at least 1 hit point and the incapacitated condition, they roll a 1d20, on a 6 or higher the effect causing them to be incapacitated ends.

Exploration/Utility

• The character gains a Ritual Book that contains all spells with the ritual tag of a spell level less than or equal to their level divided by 2 (rounded up).
• The character gains proficiency in 3 additional skills and Thieves' Tools.
• The character can cast spells from scrolls without making a skill check even if the spell is of a higher level than they would normally be able to cast or is not on their spell list.

Resources

• All uses of class features (including spell slots) are regained when the character finishes a short or long rest.
• Whenever the character finishes a long rest, they are struck by inspiration and can scribe 3 spell scrolls of any spell of their choice of a spell level less than or equal to their level divided by 2 (rounded up).

Death

• The character does not die until they have accumulated 10 death saving throw failures. They regain 1 hit point once they achieve 3 death saving throw successes.