@mikemearls @JeremyECrawford
Explain pls, why can't a druid who's seen a hippogriff shape change into one? pic.twitter.com/9zFq8POjWK

— Nicholas Cerabino (@NCerabino) June 22, 2018

Because its creature type is monstrosity.

— Jeremy Crawford (@JeremyECrawford) June 22, 2018