[sm0ke]

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.

I know that it may help but why go through all the trouble to have a rare chance to fizzle or stop invis pots, when we could either create another solution new potions or add a penalty to using invis pots or remove them all together and lower invis scroll timers idk, seems like something easier can be fixed rather than get a 50% chance to interrupt them with a firefield in certain locations while invised imo.