In response to the increasingly sophisticated technology of the Brotherhood of Nod and remembering the effectiveness of electromagnetic pulse cannons of the Second Tiberium War, GDI has used the harmonic resonance technology to create a new weapon to counter Nod - the shockwave artillery.
This weapon is not an artillery in the lateral sense - it is a single ballistic rocket with a MIRV warhead equipped with sonic emitters. Upon calling down an artillery strike, it is launched from the GDI space command uplink and flies to the designated target. The warhead deploys upon reentering the atmosphere with a distinct sound similar to classic artilleries and multiple shockwave warheads saturate the target area, disabling electronics in vehicles and structures shutting them down temporarily as well as decimating all life in the area not protected by armor.
Nod, realizing the effectiveness of this weapon, developed the Master computer countermeasures defensive power to restore power to all buildings and units alike in the event of such an attack. This power is deployed from the Temple of Nod upon request.
Shockwave Artillery barrages are a typical attack that should be frequently expected of GDI commanders who have the ability to use it, largely because it can be useful in a wide variety of situations and is moderately priced at 2000 credits per use; not a bad investment considering how useful it can be during an attack.
GDI commanders often use this ability to disable enemy base defenses during an attack, damage and disable tightly-packed groups of enemies, and to temporarily shut down superweapons to buy time before they are launched.
The artillery barrage does moderate damage to any type of target. It fires a series of shots over a short period of time that disperse in an area. Each shot has an area of effect. Light armor units will be badly damaged by the barrage, and infantry are often outright killed if hit directly. Heavily armored vehicles and buildings will take some damage, but it won't be very significant. There is only a short delay until the artillery reaches its target, this combined with its wide area of effect make it more reliable at hitting moving targets than most support abilities.
However, buildings and vehicles, even if they survive, will be disabled by the EMP effect of the artillery. If this is used during a battle, it can turn the tide by destroying enemy units and keeping some of the heavier ones from firing for a little bit. Once a vehicle is hit, it is susceptible to being hit by the rest of the barrage (though the dispersion is very high, it is unlikely they will be hit much more), as it will be disabled and unable to move. The power is indiscriminate and will damage friendly units just as well as enemy ones, so users must be careful and avoid disabling/damaging their own units.
Emphasis must be placed on the fact that it is meant to be supportive in battle, when used outside of battle its only real applications are for killing big clusters of idle infantry or shutting down buildings for short periods of time.
A clever GDI commander may notice if an opponent's power needs are particularly strained and use the barrage on a cluster of enemy power plants to shut down an enemy's power in the middle of an attack. It could also be used to cause chaos which will distract an opposing commander, causing them to spend time they could have spent on commanding normally being surprised or trying to mitigate the impact of the attack. Nod commanders can partially counter the ability if they have a Temple of Nod by activating its Master computer countermeasures ability, which effectively removes EMP effects from their buildings and units.