The Brotherhood Beam

Nod Beam Cannons cooperating with Venom Patrol Craft to hit a hard to reach target.

The Beam Cannon is an artillery vehicle of the Brotherhood of Nod. It uses a modified weapon system typically mounted on (in)famous Obelisks of Nod. Unlike the Obelisk, it fires a continuous beam instead of short pulses. Multiple Beam Cannons can converge their weapon beams into one a la Protoss Void Ray. In addition, Beam Cannons can charge friendly Obelisks, increasing their range, damage and refire rate. The most interesting (and the most situational) ability is to use reflectors mounted on Venom-class VTOLs to fire at the targets in Venom's field of view. It has shorter raw range, but the beam can be chained through multiple Venoms like pictured. Using the ability requires the Venoms to remain idle though.
The Venom Patrol Craft itself is also a good unit. It is cheap, fast, doesn't need to reload or be bound to an airpad (thus can be built in large numbers), can detect stealth and attack air targets, effective against infantry, aircraft and light vehicles, by default armed with a machine gun, but can be upgraded with a laser (basic) or heavy particle beam (Marked of Kane).