That's one thing that always bugged me about Lucas. Gotta sweetspot it to make it have a 50% chance, so dumb (I still use it but the whole thing should be 50%). And the tip is deceptive. It's past his foot. The air past your foot makes the trip.
Also kept telling myself I would try doing it out of shield on ranges where luck might shine on me but never started doing it. Ftilt and jabs are just... too good. I have had some luck using it after bounce jabs (that range where your first jab hits at a certain distance and the hitbox actually gives knockback so the second jab whiffs but the opponent is stunned a little) like jab, dtilt and at certain %s with full hop dair on grounded opponents where jab would combo for free. Got a dair, dtilt, sidesmash on someone for the kill (not talking about jab lock, just stun into dtilt just before the %s where dair would force the tech, like against Snake at 75% undiminished). Problem with this is that you have to kind of follow their di and then have it trip so it requires nasty reaction time or prediction AND some luck for the trip.
But this isn't about uses for dtilt, it's about grab releases. So, carry on >_>
OH, and I've tried grab release to dtilt and the problem to me seems that it's kinda hopeful. I remember having a Snake just spam ftilt after grab release to see if I could beat it with dtilt. Went basically back and forth and if I was the unfortunate one, I took the nastiness. If he got beat, it was like 8% and then I better hope it trips him cause if it didn't, I get ftilted anyways at like any point he was under 150. But if I did beat his attack and it did trip, the sad part was that I couldn't react and side smash. He'd have time to get up and move if he was on his toes. I had to commit to sidesmashing even before I knew the dtilt was gonna hit.
Dtilt is like, what? 6 frames or something? I'd assume most chars would just spam their fastest attack on grab release or just ***** out and pick a roll direction. So I wouldn't recommend that people do it...
But **** happens, go lucky hits (I soooo need to upload this vid of my magnet pull beating metaknight's up-b and knocking him into norfair lava).