I’m very new to Spencer (and never use Sentinel) however, I believe that fastest way to find a solution to getting out of this is by using the Record feature in training mode.
I’d just choose Spencer & Sentinel as the opposing player, call drones assist…zip dash + H attack. Record that string with a pause 2-3 second on the end, and then use the playback repeat feature.
Choose whomever you start with on your team, and keep working until you find a reliable way out of it. Maybe you’ll be able to start your own offense, maybe you’ll reset the situation back to neutral, either way you’ll find SOMETHING to do. I’d be careful trying to rely on using one of your Hypers/assists as you may either not have meter to do so, OR the timing might be strict (or assist not available)…so you’ve gotta try to find a way solo first.
(also it’s a good idea to look at some Spencer matchup video (perhaps over at FADC’s site) so you can see what others are already doing against Spencer’s zip dashing)