"Impriano.... - weak version of protego, cast while inside without concentrating on the shield. useful for physical
Contego - protects object
protego totalum - Protects an area
protego Horribilis - Protect against dark arts.
Protego Duo - Double layered shield, more efficient but more complicated.

"Contego blue beach ball!" Jay said aiming at the ball. Physical attacks... "Impriano!" he muttered quickly. And the ball looked like almost popping but it amazingly didn't and he waited for others.