Anyone know who it was who came up with the Advantage/Disadvantage mechanic for #dnd? Probably my favourite innovation from 5E. I’d love to know whose brainchild it was. We used an advantage-like mechanic in the 4E avenger, and @mikemearls suggested using something like it more broadly in 5E. I dug the idea and put it before the D&D Next playtesters to try.

— Jeremy Crawford (@JeremyECrawford) February 23, 2018