I'm really glad you enjoyed it! I'm pretty sure I ended up making the game really difficult again so it's not the easiest thing to beat.
Yeah, the scarecrow just kills all the crows on screen. It's got a pretty big cooldown but it quickly decreases the more you upgrade it, making it really good late game. The exact cooldown is 30 seconds and it decreases by 20% per upgrade.
The reduce cooldown upgrade works, but it's only by 10% so it's not necessarily immediate at first but it can quickly scale the more times you use it.
Thanks again!