[Habibi Jones]

your not realizing how hard it is, your pretty much guessing where the person is going to be that's why it's not a good fix. Like gang said try doing it in combat and not having the persons target or knowing when hes going to use invis pots

I don't think you understand the process... You don't need somebody's target man. I do realize how "hard" this is because I've tested it and I'm actually used to the concept of walls/fields fizzling people through recall so that helps me to know that it is quite possible. I can see that you've never seen this mechanism before, but if you target someones tile with a firefield scroll/wall scroll when you see them invis, it will always hit them before they recall. Problem is that now it doesn't fizzle them, so there is no point to do it. I promise you that if you were to try this, or practice it, you would see that it isn't really as hard as you think. It's not a guaranteed way to fizzle their recall, because it takes a bit of skill, but with practice I don't think you would find it so mind boggling.
All you have to do:
When you see the guy go invis, press your macro and click his tile or a tile next to him. It's very easy. With practice you will land them before he finishes recall 50% or more of the time.