"The Nova Blaster fires a fast-moving bolt of energy that will ricochet off of most surfaces." In-game description.
The Nova Blaster is somewhat difficult to aim with due to the slow movement of the projectiles. However, each shot deals 350 damage, and also provides headshot point bonus. The rounds will bounce off surfaces if they do not hit their target.
While firing from above a player try aiming at their feet so that if you miss the round will bounce back up and hit them. It is also very good indoors as the projectiles ricochet (bounce) off surfaces so it can also be useful for corner shots or shots into tunnels. The Sentinel's other secondary weapon, the Falcon, is a lot easier to deal damage with.