Initially I thought that the sentry wouldn’t be a very good unit, but it turns out I was dreadfully wrong. Its an early caster for Protoss that also has a ranged attack. One of its spells is force field which creates a force field which no units can move through. The important part of this spell is that you can cast it on top of units and those units will get pushed out of the way. If the enemy is running up your ramp you can block your ramp with a force field and split their army in half. Against a marine and marauder army it is very helpful to not only split the army but prevent the half that went up the ramp from going back down. I don’t think people have even thought of half of the possibilities of this spell.
The next most useful spell is guardian shield. While the shield is cast any ranged damaged that hits a friendly unit inside of the shield (its a pretty big shield) will do -2 damage. So if your opponent has a ranged army you can easily take a ton less damage. Instantly useful and pretty straight forward spell. Both of those spells don’t take any research!
The 3rd spell, hallucination, does have to be researched. The spell is basically a copy of the hallucination from the High Templar in the first Starcraft. While the spell wasn’t always that useful in SC I think it has some nice possibilities in SC2. For example the Colossus has a ridiculously high damage output but dies quickly to focus fire. If you have a ton of hallucinations combined with a couple of real Colossi they become much harder to focus.
So with these three spells the sentry is a pretty sweet unit. What pushes it over the top is that the sentry counters mutalisks. Yes you read that right. The early game caster counters mutalisks in addition to having some sweet spells. The sentry is fairly slow so it doesn’t do well chasing down harassing mutas, but in a straight up fight they do well.
Right now the sentries are seeing a ton of use probably because the stalker is so bad. In most early games the Protoss will make zealots and then have a ton of extra gas for sentries. The number of sentries made will probably go down if stalkers end up getting the improvements that most players think that they should. Overall the sentry is a unit that every Protoss player needs to use and understand if they want to play at a high level.
