If you are unfamiliar with the 3gate expand, here is the Liquidpedia article:
http://wiki.teamliquid.net/starcraft2/3-Gate_Sentry_Expand
The Opening
Kiwi focuses on denying IdrA's attempted 15Hatch, delaying it significantly using the typical pylon shenanigans. While doing this he performs a 3gate, dropping his Nexus at around 6:00. IdrA is going for a fast upgrade speedling/baneling style
The Cool Part
- As soon as Kiwi drops the nexus, he follows up with a stargate
- Sacrificing gateway production, he chronos out a void ray
- Instead of anxiously rushing to IdrA's base, he searches around for Overlords, while making phoenixes and dropping a robo
- Pokes with the void ray, with little success
- Cuts phoenix production at 4 and drops 2 more gates
- Uses the phoenixes to deal massive damage, taking out queens and overlords
- Builds a robo bay while harassing
- Loses the void, but instead of dumping more resources into another void, he continues harassment with just the phoenixes
- Makes stalkers, colossi and gets Thermal Lance
- Pushes, and using FF's to deny most of the banes, takes a victory
Why it works
- Keeps the zerg pinned, forcing them to spend money on new queens, overlords and spore crawlers and keeping the Toss' natural expansion safe
- Transitions into robo tech quickly to deal with a hydra response
- In the event of a corruptor response (such as IdrA's), the zerg will not be able to afford many, and the phoenixes will tank while the colossi deal with ground forces
TL;DR
Use a void ray + 4 phoenixes to harass while teching to colossus, ensuring that the zerg won't be able to kill the colossi effectively.
P.S. I'm not entirely sure how well this would work in the event that the opponent decides to just Mondragon it, since Kiwi didn't have much of a ground force while he was harassing.