Shield Forming is a particular Adept ability that manipulates a energy like substance into a small, or large, shield. It is used in Last Stand of Dead Men to stop the Monster Hunters shooting at the Midnight Hotel. Eachan Meritorious may have also had this ability.
While it has only ever been used to create large walls of energy, it is also likely that users could manipulate this into different forms. It could be formed into smaller shields, just for the user, as well as larger ones for armies of attacking forces. It may even have been able to be used in an offensive manner.