This is my second ZBrush sculpt. Learned a ton doing this - DynaMesh, ZSpheres, polypainting, human anatomy, etc.
The bumpy skin was created using the "Reptile1" alpha by Ali Minaian: [link]
The creature design was very loosely inspired by Hieronymous Bosch's creatures. Just a dude with a bird head, really... I looked at lots of baby birds, plucked chickens, and muscular people for reference.