There are quite a few casters (including buildings) in the game, and most starting out players tend to ignore them as they take quite a bit of micromanagement skill that they are not comfortable with. They are however, a good way to building your micromanagement skill. So lets look at the first one. This is for Protoss.
Did you know Chrono Boost can be used on Warp Gates? I am talking about the morphed version of the Gateway, your primary source of building units. It halfs the recharge time of warping in units! So instead of waiting 23 seconds to warp again, you can do it again in 12! Come patch day, it will be 14 seconds, but that is still a fast way to get units out, Zerglings don’t even come out that fast! If you have an expansion and both your Nexi are pretty full in energy with say about 6 Warp Gates, you will still have spare energy remaining and have produced 24 supply worth of troops (1/8 of your max population) in a matter of 12-14 seconds.
Another Protoss unit that has some interesting tricks is the Phoenix. It can move and fire much like the Diamondback from the single player campaign. However it requires some micromanagement as it doesn’t simply move and fire automatically. You can fire, move, fire again and keep moving. It requires very fast hand speed and knowing your hot keys.
This trick is actually something people have rumored it will work but in fact it doesn’t. High Templar cannot Feedback an Orbital Command. It only works on units.
This one I didn’t know about until recently. We have all been trapped or halted by the Protoss Sentry’s Forcefield. It can be a real pain. However, if you have some Colossus, you can use them to break the forcefield! Simply order them to walk through it.
Ghosts are a unit that most people will overlook as there attack isn’t that strong, and they die very easily. However, when you add a Ghost to your unit makeup when going up against a Protoss player, the results can be lethal for the Protoss Player. There Emp Round can take down the shields of any Protoss unit. This is especially useful against the Immortal as their damage reduction only applies to their shield. Once their shield is down, no more damage reduction is applied.
Another way Ghosts are useful is against cloaked units. Most people will think that using EMP against a Banshee reduces its energy to 0, thus it comes out of cloak, or that’s at least what it did in Brood War. However, when it is used against a unit with a permanent cloak, like the Observer or Dark Templar, the EMP will actually knock the unit out of cloak temporarily! The catch is, you have to know where the unit is to use it.
And last but not least is the Zerg Queen. Most people will keep them in their base and puke Larva and poop Creep Tumors. However, their more commonly unused ability is Transfusion. This ability instantly heals 125 health. This is great to use on units like the Ultralisk or Hydralisks. They cost no gas, have a very long ranged anti air, and there is no cooldown for the spell, so you can spam it on targets who are getting focus fired. However the down side is Queens move very slow on ground that isn’t creep. So building a few extra queens and getting some Creeping going is a great way to fix that, as well as giving you excellent vision across the map.