What is the most difficult part of creating an effect?

Alex: Coming up with a good idea. It has to be as original as possible, look good, and fit the design description. Now multiply that by 300+ effects and the well starts to get dry fast! So how do I stay fresh? Starbucks Coffee. One crunch time I had a 12 shot espresso latte. I spent the whole night afraid to move around for fear my heart would explode out of my chest. But, the other side-effect was the ability to see into time, and I used that opportunity to steal my own ideas from the future to use now.

So, to recap, lethal amounts of coffee and self plagiarism are the most difficult parts of effect creation.