You know how with 4~2,1 the high and the low at the beginning hit at the same time? The trick is that if only the low hits the 1 is guaranteed. You have to be in perfect range, almost as far as you can get so only the tip of her foot hits while her hand misses.
There's so many uses for this. You can actually punish some moves with it that have push back, like a deathfist. The 1 wallspats so you can get in the right distance and mix it up with elbow. You can use it for oki, like after the mad axes if they stand straight up they're in perfect position or after elbow hits dash up.
Only problem is if you screw it up you're getting launched.