Dealing with mutas in PvZ

The Prequel

So a sad game ended happening. I was killed by mutas T__T. After watching the replay I was, however, filled with ideas.

1. Basically if your armies are equal in size or if you have correct units the mutaing opponent does not seem to want to face you in a direct battle. 
2. They will be relaying mostly on the mutas and spines. The amount of mutas and spines seems to be relatively feeble up to 12 minutes. 

The Sequel

Based on there two observations I came up with some actual ideas.

1. If they want to defend their base they will have to engage you in a direct attack. So attacking with an army superior to mutas would be desirable.
2. Few immortals are required for knocking out spines.
3. The attack must happen before 12 minutes.

From Game 2
Lost too many probes. Make a better wall and sentry better. When to make momma in PvZ?
Tech faster to ht if you see mutas..

Game 1 - worked
Game 2 - almost worked XD