Basically, you have to jump while holding towards the opponent and jump very quickly again. It's easiest with two jump buttons but you can done it with one without much trouble if you're fast enough. You should get a grounded footstool which will combo into dair.I recommend using the c-stick to dair, because you have to perform the dair immediately after the footstool. If you lack the c-stick it's just a little harder though because you have to roll the stick from forward to down. It's kind of odd because it doesn't look like the footstool is guaranteed at all, but they cannot shield before the footstool, so it
is guaranteed because the footstool animation will cancel any other attempted animation. Only works on fastfallers though.
Here's an example match where I use some of the tricks from my guide. I use the footstool trick at the 2:38 mark to better punish a whiffed fsmash.
However, I screw it up at 3:40. The timing gets tighter as the percent goes up, but I believe it's still doable at 10%, I just didn't footstool fast enough. You pretty much have to catch them in a 2 frame window where they've landed but shield won't come out yet, this gives about 3, 4 frames to catch the footstool after the dthrow lag is gone. This is much easier if the fastfaller is light like Shiek or Fox, because that means less lag at the end. That said, I need to check if this is possible on Falcon because his heavy weight might add too much endlag to the throw.
Thanks for the info on the Falcon combo, I admit it was one of the few things in this guide which I hadn't done in a real match yet. I'll change it now.
