Learning SC2

The Sentry’s Force Field ability is probably one of the most important tools Protoss has. It can be used to defend when an early attack could not otherwise be defended or to assault your opponent while forcing their army into a bad position.

Games can hinge on good Force Fields, it’s not uncommon that an incorrectly placed Force Field will cost a Protoss player the game. It is crucial for your progression as a Protoss player to at least have a decent grasp on Force Field use.

In preparation for this article I looked at a lot of games from three professional players well known for their near-perfect Force Field use: White-Ra, iNcontrol and oGsMC. I have also been doing a lot of work on my own Force Field use, with great results.

How To Cast Force Field

Assuming ‘F’ is the hotkey for Force Field (F is the Default) the to best ways to cast it are:

• ‘F’ > Click each Force Field individually, or,
• Hold ‘F’ down and click for each Force Field you want to cast.

This is purely personal preference, I use the first option because I feel it makes me place each Force Field a little better than if I use the second option. Try both and decide which is more comfortable for you. Do not ‘Shift+F’ Force Fields as it causes the Sentries to cast after they kill the current unit that they are attacking.

How Many Sentries are Needed?

The following is based on my experience and my observations on professional Protoss players. I give a range of recommended Sentry counts so that you can adjust depending on how good your Force Field placement is. If you are not confident that you can be very efficient with your Force Fields use the higher Sentry count suggested.

• When defending one base with a ramp 3-4 Sentries is enough to block the ramp for as long as you want.
• When moving out to take an expansion a minimum of eight Sentries is recommended against Zerg. Eight will allow you to have enough Force Fields to easily defend any Zergling attacks and small Roach pushes for a good amount of time.
• When moving out to attack or secure further expansions 8-10 Sentries is recommended to effectively apply the techniques discussed in this article. This is true in any matchup, especially when you are using Colossus in your army. Effective Force Fields will greatly amplify the effectiveness of Colossus.

Force Field Techniques

The Force Field ability is very versatile and its uses are only limited by your creativity. The following are common techniques that you can use to great effect.

Ramp Block

This is the most simple of the techniques and only requires a bit of timing to do well. Force Fields are used to block enemy forces from coming up (or going down) a ramp. You can place the Force Field to completely block enemy troops or you can attempt cut the army in half as it comes up the ramp netting you a few easy kills.

In the same game WhiteRa uses a Force Field to trap a few Zerglings on a ramp. Easy kills.

Open Field Block

Used to prevent enemy forces from engaging with your army or to prevent flanks. This technique should be used when you want to completely avoid an engagement or if your troops outrange those of the enemies, a common thing for Protoss. You can improve the effectiveness of this technique by utilising chokes, walls or buildings to help block the enemy’s movement.

Zerglings can easily be blocked by using Force Fields in the choke created by the gateway

oGsMC blocks off the Roaches allowing his Stalkers and Colossus to attack freely.

Cut and Trap

Using Force Fields you can cut an enemy’s army in half and trap some of the units to be easily killed by your Zealots. Using this method you can safely chip away at the enemy’s forces whilst taking minimal damage yourself. You can also trap any units caught off guard by creating a concave of Force Fields behind the enemy’s units. I group these two techniques together because cutting an enemy’s army is the same as trapping a portion of it. Using these methods you will never have to engage the enemy at his full strength.

oGsMC uses Force Fields to trap a few roaches that are separated from the Zerg's main army.

In this game I manage to cut a few units off from my enemy's army giving me easy kills.

Bottleneck

A bottle neck is essentially a small choke, it restricts movement to your enemy’s army and causes them to bunch up into a gap. This technique works with splash damage from Colossus or Psi Storms and it also tempts all but the most experienced of players into engaging when they should be pulling back.

The bottleneck created here forces the Terran opponent to either pull back or fight a bad engagement.

Here multiple bottlenecks have disrupt the enemy's arc and maximise the effectiveness of the Colossus.

A Few Tips

Following this advice can help you use your Sentry’s energy more efficiently and help you to have better engagements.

• Troop Movement is extremely important: engaging at chokes or near walls will make your Force Fields much more effective.
• As the enemy approaches throw down one or two Force Fields pre-emptively, then if he continues past those complete the cut. This makes cutting his army easier as it makes a temporary choke-point.
• Try to not overlap your Force Fields, doing so wastes valuable energy that could be used on more Force Fields or Guardian Shield.
• If you have High Templar in a control group casting Force Field becomes difficult, set your Sentries to a different control group to make using Force Field quicker and easier.
• Calm Force Fields are well placed ones. Easier said then done. Try breathing out before you spam them everywhere.

When Force Fields DONT Work (Or, How To Deny the Protoss Force Field Use)

In the following situations Force Fields will hinder you or flat-out not work, avoid over producing Sentries if you encounter one of these.

Against Massive Units

Colossus, Thors, Ultralisks and Archons (as of patch 1.3.3) are all ‘Massive’ class units and will break Force Fields upon contact with them. If your opponent is leading their attack with these units do not Force Field, instead use your energy on Guardian Shield and Hallucinations.

Against Siege Tanks

Siege Tanks are generally stationary and have a long range, using Force Fields when facing a large number of tanks will help your opponent more than you. However, if you can, use Force Fields to prevent Terran’s units from pulling back into range of their tanks using the Cut or Trap techniques.

Against Air

Yep. Doesn’t work against air units.

When Your Opponent is Highly Mobile

This one is a little different. If your enemy is playing a highly mobile game (using fast units and drops or other harrasment) Force Fields become limited in their usefulness overall. You can still use a few Sentries to prevent some attacks but most mobile players will simply attack elsewhere. In this situation limit your Sentry production and instead focus on your own mobile units to counter or build up for an attack.

Has Force Field use been something you have struggled with or are you the oGsMC of your division? I am still having trouble with making sure that I don’t overlap them too much. Let me know about your Force Field skills in the comments below!

A special thank you to Ramzdale for helping me get a few of these awesome pics!