Ryoko's Guide to the Yokai Realms, pg 218
Prerequisite: Improved Extra Attack feature
You have studied the fighting styles of others and learned to mimic their techniques, granting you the following benefits:
• Increase your Strength or Dexterity score by 1, to a maximum of 20.
• Choose one class from among barbarian, bender, fighter, monk, paladin, and ranger. You can use the 7th-level benefit of the Improved Extra Attack feature from that class a number of times equal to your proficiency bonus, regaining all expended uses when you finish a long rest. You can only benefit from one Improved Extra Attack feature per turn (choose when you make your first attack).
You can select this feat multiple times.