Okay, so stabbing this thing isn't working... what next? All of the magic available to you will probably do something to light up the area, so that's not a concern... but you need to act before it can attack you, and you know it's just about to do that.
Without giving it much more thought, you reach a hand forward and let sparks fly. The tank stops moving, but is very clearly still functional, since it hasn't dissolved yet. You decide that this is as good a chance as any to get away from it.
"...Did you just pick a fight with a Shadow immune to physical attacks?" Shinjiro-san doesn't seem to be doing anything. Then again, with how much nothing your spear did, you suppose there's not much help he'd be able to give.
"I guess?" You throw another bolt of lightning. "Do you think the dolls on the other path would have been easier? I mean, I wouldn't want to get swarmed..." You aren't entirely sure why you're asking for advice from someone who freely admits to being a figment of your subconscious' imagination, but Shinjiro-san's always had good advice for you before. At the very least, he's probably the most likely person in the whole dorm to be completely honest with you.
The tank continues blocking the corridor. Once it starts moving again, it starts taking aim at you. You zap it again.
You realize, of course, that you can't do this forever. If the tank pushes you out to the split in the road the dolls might join in, and then you'll have to deal with everything you were trying to avoid. But the Shadow doesn't seem to be very good at shifting where it's aiming at, so as long as it doesn't start rolling forward...
"I mean, at least I'd be able to fight the dolls," Shinjiro-san points out. "...Probably. You don't exactly see them around Tartarus."
...Is he implying that it's relatively normal to see tanks around Tartarus? You don't know if you should find that exciting or horrifying. Given how you've resorted to keeping up a steady stream of lightning so you don't get shot, you're leaning more towards horrifying at the moment.
You aren't sure, really, how to tell how hurt a Shadow is, but you think you might be making progress. "They did look a lot less sturdy than this." Not that you can go back and fight them instead. You've missed your chance. You throw another lightning bold. "But they probably wouldn't be this easy to hit." You wonder if you should be talking so loudly, or if it'll just bring a bunch of dolls down on your heads.
But then, with all the electricity that's been hitting it, the tank doesn't seem like so much of a threat as something to drain your magical energy- you can feel yourself starting to get tired of it.
...Maybe it's not too late to run? You could lose it in these passages, probably...
But before you can do so much as begin to formulate an escape plan, Shinjiro-san speaks up. "You know how Shadows are a lot weaker when they're knocked down?"
You're aware of this, yes, even if this thing recovers too quickly for you to do much more than spend your energy keeping it down so it won't actually attack. "Yeah."
"Well, if multiple people were to team up on one, it wouldn't work the same as a regular attack." You have no idea where he got that hammer from, but that's probably not the only thing you should be questioning here.
[ ] Keep doing what you've been doing.
[ ] Attempt to retreat.
[ ] All-Out Attack!