Oh sorry, Smash terminology is really bad so don't worry about it. Vortex basically refers to when you get caught in a series of frame traps. For example, Fox Up Tilts you, does Up Air, and you have to airdodge. Fox autocancels the Up Air, and is then able to land and Up Tilt again before you can act, repeating the situation.
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Some random observations from footage and stuff (the person who linked me this asked not to share, sorry):
-Fox's Jab tumbles at 0%, but there seems to be a sourspot at the end which ... doesn't? I just saw footage of unstaled Jab not tumbling Roy at 25%, but it tumbles him at 0% in the next game. It looked like the tipper of jab ender though, so that might be it. Jab at 0% tumbling is crazy good, though.
-Dair's multihits pop grounded opponents up. It actually has enough frame advantage to combo into Up Smash and Up Tilt which is pretty funny, but the move overall seems worse.
Random thoughts on viability etc.
-DTilt seems ridiculous at low-mid% and needs labbed
-SH Fair as an combo extender actually seems okay now, even if you can't FF dragdown, the landing lag is low enough to set up vortexes or whatever
-Nair is broken