[G] Belial's Comprehensive Guide to Everything ZvP! - Page…

^ The time it takes for Toss to bust the natural would be enough time to get mutas out. It wouldn't really make sense for Toss not to take down the third at the same time he's going for your natural. I mean, the third and rocks at the third take about the same time to kill, that's all you really need. All you need to make sure of, is that Toss doesnt race up into your main and kill the spire before you've been able to pump about 25+ mutas. I mean theoretically, if you put your spire in your natural, and then toss goes move-command straight into the main, or goes to the natural, kills that, then main, you'd be fine too. Hell, you could actually proxy the spire, and not make any spines at all in the natural, instead making them at the furthest base Toss attacks first to buy time, although that doesnt really matter too much either.

You aren't making the spines to hold the Toss push. You are making the spines to discourage Toss from going move-command into your main, and killing the spire there. Theoretically, if you proxy the spire, you don't need to make spines at all, or if you make the spines at your third and Toss goes to your main instead.

But you can't know for sure where Toss is going to go, and Toss will figure you put the spire in your main, making your main the go-to if he knows you are going quick mutas. So that's why you put spines in your natural, to buy time for the spire to finish, so you can get those mutas out. By putting spines in the natural, you force Toss to make additional warp-ins before he can bust up the ramp (or else you can come home with the lings and just kill his entire army of sentry/immortal with only a single warp in of units, as well as when the mutas pop). Thereby, forcing Toss to go to the third in the meantime. I mean it'd be awesome if Toss just sat afk in front of you base, waiting for his army to get large enough to bust up.

On Ohana, if he tries to go around and bust the rocks, you just re-root the spines to that side. If he moves toward the main ramp, uh oh, you just re-root the spines! And while this goes on for about 40 seconds, Toss has already lost every base, and you've been able to fully mine gas off 3 bases and will have 25 mutas very, very quickly, and it'll be much easier.

The base trade is a race against the clock, and Toss needs to do 2 things - kill the spire asap, which he can't if you make it in the main and make a ton of spines in the natural to at least buy time, if not kill his army if he's dumb enough to go straight into the natural before he has enough warp-ins, and cut off mining at as many bases as possible, which won't happen if he has to go through rocks or spines.

Really, going quick muta base trade with mass spines in the natural just hard counters not only immortal/sentry, but robo play in general. Hence, that's why you don't do immortal/sentry all-ins, it's prone to just being countered by preparation. If you actually go gas, lair, spire quick enough, you don't even need the spines (although that may require the spire be proxied).

Yes, making sure all overlords escape is a great tip when going base trade against immortal/sentry. That's something I'll add. If you watch the reps, you'll see I make a conscious effort to start moving all overlords over dead air as soon as I know it's a robo build. And yea, spewing creep will continue if you start it before lair goes down.

but it takes a long time to work down rocks. You just play a game of uproot spines over and over, and as you mine more and more minerals as toss' army does less and less, you can make more spines, more mutas, more units. Immortal/sentry is a timing, if he doesn't accomplish enough damage by a certain time, he just has no chance. With your spire up, and 15+ mutas started all at once when spire finished, the clock ticks from you having 15 mutas which won't beat the immortal/sentry army straight up, to 25+ mutas, which will just a-move against any immortal/sentry army and crush it easily.