It is a very satisfying way to kill someone but my big problem with using Up + B this way is that if you miss, you put yourself in a really, REALLY awful position. It's massive risk imo. Out of interest, where are your opponents when you use this move Edrees when you're scoring kills at 130%? Are they really near the top?
As for the lightning flash, it can appear when using any move and in my experience it normally indicates that you've done something with sufficient knockback to KO your opponent. Next time, look out for when the lightning flash appears and you'll find that normally precedes a KO.
I actually rarely get punished for it. Or if I get punished it's just a grab or dash attack. It's hard to land a smash attack on her because her fast fall after this is pretty fast, and you can do all sorts of mind games to trick people where you are going to land by re opening and re closing the parasol. Also you can go for the ledge if you whiff it. Personally even against good players in tournament I rarely get punished for this, but I don't abuse it, I just do it when I'm sure it will connect. I'll wait for air dodge then do it. If you see the air dodge come out this has a 100% chance of connecting.
The real thing this does is get into someones head. They will be super scared of it everytime they face peach if it ever kills them, and they will be airdodging like crazy while above you, making up air's easy to land. Also I don't even try it against some characters. But some characters are so defenseless from below. Ness, Rob are easy to do this on.
Yeah my opponents are high up. I wouldn't say near the very top, but high up there. Rage is definitely playing a role into this.
I killed a yoshi at 99% who was at the very top though. I did have rage for it though.
I killed someone, I think a Mario, with UP B out of shield on the ground of FD around 140%.
Also, the whole point is that you up air chain them until they get high enough to do this. It comes out much faster than up air and you can do it after using two jumps if they are still too high for you, so it's a situation where you can't do another up air.
Mikey - that is amazing information. Sorry I didn't see that the first time around! The set knockback thing is new info, and I'm so taking Rosalina's to BF.