Strategies:-
Ghasts are pretty much one of my favorite units as they can literally tear up high armor and HP units with their frenzy of high damage attacks. Their swords deal a great deal of damage in very short amount of time. With low cooldown but melee range, these Ghast are the type to run into the frontline of enemy units, kill as many as they can and die there. Ghast are effective against anything that are slow. Range to them is not a problem as they can run very fast at high levels and MKs.

Defend/Support:-
A Ghast's role is to defend and support. With a tech 60+ blade, they can tear up a group of moths even before they notice them under their cloak screen. Ghasts can also cause havoc amongst a group units like the Spirit as its blade can cut several units in a short time. In a support role, they must be under cloak to be able to find the arbs who are targeting your allies. Using their blades, they can kill the arbs without much detection.

Offensive:-
In a Ghast's offensive role, its more of a suicide mission to kill everything that they can, and try to flee. With their speed, they are able to chew up a couple of manticores, fast enough to avoid possible detection from nearby enemy units. However, without cloak, the Ghast is very vulnerable to enemy artillery fire as they do not have enough space or weight to equip armor in early stages. But, at higher levels, they can take on the role of mass killings as they are able to withstand a lot of damage as well as do a lot of damage.