If there ever was a map suited for multiple hatcheries, this would be it. I recommend you build three of them right away. One east of your starting one, as close to the crystals as you can get and the other just south of the vespene geyser that is located to the northwest. You'll want to get about sixteen drones working on minerals, and three on gas (you'll find more vespene soon). When all your drones are done, start building your three basic needs - a spawning pool, an evolution chamber and a hydralisk den (make hydralisks asap to defend!). Then, expand the creep. You have a lot of area to defend here and some static defenses are surely going to help, even if they only slow the Protoss down. Keep them spaced, though. You should keep a full group of hydralisks home to help the sunken/spore colonies you build.

Now it's almost time to think offensive. Unfortunately, your first choices are both poor for ground assaults because of the ramps that lead to the Protoss bases. For that reason, you'll want some guardians to help you tackle at least the leading edge of the protoss defenses at the top of the ramps. Six should do just fine, along with 12 hydralisks and 24 zerglings. Wait for the path to be clear before you charge the zerglings into battle. As always, use some scourge to see if there are any reavers in the area which your guardians can destroy.

This is a key spot for you, as the vespene geyser will double your gas intake. Whether you utilize the minerals or not, do take control of this geyser!. Even if it's depleted that's more than you had before. Now that you're richer, you can easily afford ultralisks. Get four of them, 12 hydralisks, 6 guardians and 24 zerglings and prepare for battle. The next target can be seen in the next screenshot.

This target happens to be the base east of yours, this time. The ramp that leads to the plateau this one is on is to the north, this time. When you get near that ramp (after the battle) you can see a vespene geyser to the north on level ground. Just like the last one, this battle will not be very hard with such forces. It will remove a major thorn in your side when you conquer it. With both of those bases gone, the protoss will have less unit production capacity, and none quite so close to your base. Build an extractor and hatchery on the geyser even if it's depleted, once you've destroyed their base. You can build yet another extractor/hatchery combo on the geyser I mentioned earlier. Now it's time to destroy the Protoss.

You should have loads of resources and about five hatcheries by now. Use them. Get a total of eight guardians, 24 zerglings, 4 ultralisks and 12 hydralisks. Now proceed to the area in the screenshot, that is, toward the temple. Get your forces into position outside the temple area, where it's safe then build about 18 scourge (3 hatcheries can produce these in one go since you get 2 per egg). Send them into the temple area using the attack area command. Make sure you knock out that carrier. Now you'll be able to take those guardians in and soften the ground forces without harassment, especially if the scourge knocked out the scouts too.

Rush all your forces in but try to keep them at least somewhat organized. If you've got your hatcheries hotkeyed (you should, darnit) you can set the rally point to the center and call in mutalisk reinforcements as you did on earlier missions. Wipe every last building out, but avoid the temple for now.

This is the hard part. There are a couple of archons guarding the temple, just beyond the area in the screenshot. You're going to want at least 24 zerglings to soften them/absorb damage and at least 8 guardians and 12 mutalisks to fire on them while they do so. Really, the archons don't take that much force - you just want to make sure you control the area for the next step. Keep sending in more mutalisks. Even if you fail, at this point you've caused critical damage to the Protoss. When the temple's destroyed you're to bring the crystal to the beacon by the temple. It's a boring wait as the drone carries it all the way up there, but since you've destroyed almost everything Protoss it should be a safe journey. Escort it with some mutalisks to be on the safe side.