Does Hold Person spell works on undeads?

Does the word “immediately” in the Flurry of Blows description preclude this from happening?

Is there an official answer to the way spells care about a monetary value?

Battle Master Feinting Attack maneuver discriminates against polearm users

Would a Way of the Open Hand monk be limited to picking a single monk weapon?

Can you cast feather fall in time with 1 reaction, considering the “Xanathar’s guide” rules on falling?