One of my player is using polymorph at himself to be a T-Rex, Isn’t he abusing?

@JeremyECrawford One of my player is using polymorph at himself to be a TyrannosaurusRex.Isnt he abusing?Is that the intention of the spell?

— Enrique Delgado Torr (@enrikisinger) February 27, 2016

You can cast polymorph on yourself, provided you can see yourself. #DnD https://t.co/MQ0FzPkrYX

— Jeremy Crawford (@JeremyECrawford) February 27, 2016

@JeremyECrawford You can always see your hand, for example, Do you mean you need to see the whole body in order the spell to work?

— Enrique Delgado Torr (@enrikisinger) February 27, 2016

To see yourself, just look down. Something like blindness or darkness can prevent it. #DnD https://t.co/gfyXUwMhhi

— Jeremy Crawford (@JeremyECrawford) March 1, 2016