Starcraft 2 : getting gold on Psionic Assault

Solution 1:

I managed to get a perfect score (300) on this. Here's how:

• Use sentries as attackers. With 11 of them, your DPS is high enough, but if they start dying, you're screwed. You don't have to lose one single unit.
• If you feel like storming a big blob, try killing them with sentries first. Storm should not be used against every wave. You can skip storm completely for the first 5-10 waves or so.
• Keep sentries in 2 separate control groups in order to deal with flanks.
• Save right after and before every wave.
• Vary your casters. Try to minimize the number of units sitting at 200 energy. Always use the unit with the highest energy for casting.
• Templar energy is worth much more than sentry energy.
• Don't morph any Archons. You don't need a single one. Storm is much more useful.
• Guardian shield is useless.

And for some specific waves:

• When you face big numbers of reapers, wait for them to jump up the cliff, then forcefield around them and storm. They will jump down and back up, because the AI is stupid.
• Use fake Archons to tank the Ultralisk. (The Archon is generally the best hallucination.)
• Big units with energy should be feedbacked. Ghosts can be stormed, but I recommend feedback for the first wave.
• The Collosus is the hardest wave. Use one or two hallucinated Collosi for this one.
• Use fake Void Rays against the Battlecruiser.

Solution 2:

I found this video helpful.

• The best way to use psi storm and force field together is to cast several forcefields in an arc (rather than a straight wall), so that enemy units will cluster in one place. This makes the storm much more effective.
• Use hallucinations (archons) to distract units which get inside your area (mainly reapers). Do so before they have a chance to spread out.
• Use high templar in pairs until they run out of energy. Once they're out, let them recharge while you use another pair. Toward the end, you might want to make a couple archons. Use them the same way as the hallucinated archons, but try to let the hallucinations take most of the damage.
• Use a single guardian shield whenever your sentries are taking fire. Your templar should hopefully never take fire.
• Don't overuse psi storm. You'll need to use the sentries to finish off enemies after they've been softened up by a storm or two.