Strategies:-
Spirits are long range support units. Their high weapon range and sight gives them the edge in the hit-and-run tactic. Their range and sight is about twice the amount of a normal unit. Though fast and agile, they are prone to faster units like the Pegasus or the Gryphon as their HP and Armor are quite low in low stages. Their ability to cloak and use Radar Evasion is excellent against artillery units. They can also cause havoc amongst close range units as their range and cloak makes them hard to detect.

Support:-
Spirits are somewhat like Mephits, only that they are faster. Their long range and low cooldown allows them to pick off slow units faster from far much more effectively than any other unit. Their ability to evade Radar and Sensor scans allows them to be undetected by radar and the unit targeting them will have their range cut in half. This makes Arbalest an easy target. Just turn on sensor evasion, go near an Arbalest and turn off. The Arbalest cannot hit close range unit thus by cutting its range in half, it almost cannot hit you at all.

Raid:-
Raid is one of the most effective methods to find arbs and balls. Send in a group of 6-8 cloak spirits with at least a 15 range weapon and with targeting goggles to maximize the effect. With the long range weapon and goggles, you can scout the parameter for nearby arbs that may target your allies. Turn on cloak and go in to kill the arbs. If the arbs have some defenders, concentrate on the arbs before attacking the defenders. Then, move back a little and press S to stop. The spirits will then auto-target anything that comes into sensor range. Continue this process and you can kill alot of units.