That's very interesting way of dealing with things, certainly food for thought

. I sort of went off mutas for quite a while because stalkers can eat through them reasonably well. If I did use them, it'll be at most ~6-7 for harass and then build up a roach/hydra army whilst creep is spreading. It seems to drag out the game somewhat but it seems to work quite well. Do you typically just mass mutas then at tier 2?
Also in zvz, would you follow similar tactics? Again I've found massing mutas results in them being fodder for hydras, so just a couple to keep them on their toes is awesome.
Apologies for all the questions, feel free to ignore if you're busy, it's just I don't ever get to talk to high ranked players really

. I feel like perhaps I'm doing something wrong with mutas and I should be using them more...
Not at all, i enjoy answering questions, especially if their going to help
My standard ZvP tactic is to generally harass with 6-8 mutalisks. this will give me a chance to slow them, and scout out their base a little more to see their next tech. If they have gone robo, i'll continue to pump mutalisks and start upgrading +1 carapace for air/ground.
If they go Stargate, i'll tech switch to hdyra roach, and get a couple of Spores at each expo to prevent any harassment
If they go tempar tech, i'll get my tech builds for Roach/hydra, but continue to pump mutalisks/Lings with upgrades. When they commit to making archons, i'll instant tech switch to Roach/hydra. This is the beauty of Zerg, providing you have the building, you can produce whatever unit you want in mass and very quickly. You'll see players like FruitDealer do this, as soon as they gain an upper hand in the game, he'll wack down as many techs as he possibly can and expand.
Its all about your style though, i prefer Muta/ling because its extreamly mobile, pretty much forces them to switch to stargate tech, which for them takes time, so their always on the backfoot. thats my style.
Some players prefer a macro intensive game with Roach/Hydra/Ling and constantly pumping and expanding to match the protoss and eventually wind them down.
ZvZ at the moment, seems to be favouring a fast expansion build into roaches, and then a late transission into T2. hydra, muta or infestor.
I also have a lot of success with 1 base mutalisk. This beats any baneling or roach build, gives you map control and the containment ability. They litterally have to tech up to T2 to come out of their base. Only vulnerability is early on.
Remember though, these are only guidelines, the main thing you need to do is react to what the enemy is doing.
EDIT:
Hehe
When I was in bronze/silver I found that I relied on mutas too much and that they'd just push with a more effective army and win. Possibly cutting them totally out of my builds was a little extreme

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Time to experiment me thinks

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This is what i found when i got higher up Diamond. Mutas just didn't seem to work as well as they should for your cost. The key is, when you harass, don't lose or risk any loss of your Mutas, you NEED them for when they make a push out fo their base.
the idea behind mutaling is that they compliment each other extreamly well on the battlefield AND on your economy.
off 2 base it kinda goes like this:
- 1xMuta everytime you get 100 gas,
- when you don't have gas, Drone and Zerglings.
- Slot in Carapace upgrades to null out their +1 weapons grade.
- Mutas counter the Sentry/Zealots
- Zerglings counter the stalkers.
Priority on attack for your mutas should be Sentry (if visible)// Colosi --> Zealots --> Stalkers
also bare in mind, you can NEVER have enough Zerglings
Ive beaten Diamonds 1.9k Ratings and up with this kind of play style, it is insanely hard for protoss to counter. Even the good ones! they mainly rely on Zerg making micro mistakes allowing them to pick off units. Or being lucky and opening with Pheonix.
should they open with Pheonix, just go roach/hydra, no point in even attempting air supremacy agaisnt Pheonix.