Art of Improvisation

Through years of training, you have learnt to turn any random object into a martial arts weapon.

• You gain proficiency with improvised weapons.
• Improvised weapons are considered monk weapons for you. A one-handed improvised weapon is considered to have the Light and Thrown properties (range 20ft/60ft). A two-handed improvised weapon is considered to have the Two-handed property. A large improvised weapon is considered to have the Two-handed and Heavy properties. The damage type is considered to be Force damage. The size of the weapon is determined at the DM's discretion. 
• As a reaction, you can use an improvised weapon for defense. A one-handed improvised weapon grants +1 to your AC, a two-handed improvised weapon grants +2 to your AC, and if a large improvised weapon can reasonably hide your whole body, it grants 3/4 cover (DM's discretion). When you use this reaction, roll 1 martial arts die. If the result is 4 or lower, a non-magical improvised weapon used in this reaction is destroyed. If the result is 1, a magical improvised weapon used in this reaction is destroyed. You can use this reaction a number of times per long rest equal to your proficiency bonus.