1) Depending on which order you're doing the missions in, you can probably get mercenary marines too.
2) Use more Medics. With units like mutalisks, you probably want more medics than 1/7, probably closer to 3.
3) Build defenses (Turrets and Bunkers). Most of the air attacks came to my first base, 1 bunker (marine, marine, firebat, marauder) 1 turret, 2 SCVs was more than enough to fend off all attacks.
Note) Reapers are nice, but they are most effective against buildings, or exploiting terrain (hitting a weak side up a cliff), they work okay in a group with marines.
Here's what I did (hard difficulty):
After initial defenses at my main base (the aforementioned bunker defenses), I got a few reapers, and traveled around the north area collecting pallets and more reapers. Running back to the medics at the base as needed.
Then, as I needed to move to other bases (heading south towards the brutalisk next), I used the provided secondary command center with 4 mercenary marines and a few medics with the 6-8 Reapers to protect it. The attacks against it were minor, but I did build a bunker and had an SCV repairing it.
I generally used this same force (3-4 medics, 4-6 mercenary marines in the bunker, 6-8 reapers) wherever I moved the command center. The reapers would jump ahead to the next mineral deposit to clear out the enemies, and run back to the medics as needed, and the rest would stay by the bunker which was just up the hill from the minerals.
I was able to completely eliminate the enemy's bases, and got the "Scenic route" achievement.
Best Answer
How I personally ended up doing it: if you notice, the very top left and top right spots will NEVER get hit by his tentacles. I would put all my primal hydras and roaches in either corner and have them attack Zurvan. You can not fit all of your roach/hydras into the top positions, but at least 50% of them will not be attacked by Zurvan until the final stage. When they are hit, move Kerrigan up and use your
The safe spots are circled in the blue (screenshot taken from PsyStarcraft replay, see first comment on question for link)
Mendspell to heal her and your roach/hydra/ultra.I would then micro Kerrigan and the Ultralisk to both kill minions, and to attack Zurvan as much as possible. When minions came up, I would use Kerrigan's special abilities to burn them down while the roach/hydra took down Zurvan. It's also important to use Kerrigan to group the minions together, and use
Psionic Shiftto attack as many as possible. When the acid spewers are summoned, make sure you burn them down first (they will spawn in a group of 2 with an ultra) as they will two shot your hydra/roach if you let them get attacked.At the final stage (roughly 10-15% life), I only had the Ultralisk and Kerrigan alive. I was able to defeat Zurvan strictly with them and eventually with Kerrigan only. With her spells she can solo Zurvan alone. I used
Picture of the last stage where Zurvan uses a cone shaped attack. This is where I used
Leaping StrikeandPsionic Shiftto mainly get out of the way of Zurvans Attack and to burn the minions down faster. AndMendwas used as much as I could get away with it, to keep Kerrigan topped off in case I would slip when microing.Psionic ShiftandLeaping Strikemainly as evade and for burning minions. (screenshot taken from PsyStarcraft replay, see first comment on question for link)I also beat it all on Brutal, and he was my biggest test. It would take me about 5 attempts, but after I started microing better I was able to take care of him. Hope it helps :)