They sent for help, obviously, when the assault began.
Her best guesses as to why it hasn't come are that this is a coordinated demon offensive, every fort is under this much pressure, and they're saving the highest-value ones first; or that whatever demon blotted out the sky also did something that prevents communications in or out -- it is blocking Teleports, so it's not that unlikely a theory -- or that the end has come and all is lost and Cheliax has no one to send.
Regardless, there's not actually much you can do as a barely-fourth-circle wizard who has been out of spells for nine hours. She's been lying on the ground to avoid the worst of the choking black smoke, relaying Messages and putting Light where people want it and cauterizing injuries with Acid Splash. She tried binding a familiar to have something to use for scouting; it was useful for three hours and then got eaten.
The Messages have been getting steadily less encouraging. If she were capable of taking solace in anything at all about this situation she'd take solace in the fact that the fancy fifth-circle wizards, the ones that aren't yet dead, are doing the exact same thing; they're out of spells too.
She is nursing a stab wound, from one particularly unlucky arrow, but it's not going to kill her at least until tomorrow and is therefore barely registering among her concerns.
She relays requests for backup and requests for lighting and occasionally flicks off an Acid Splash and she thinks about how this isn't enough, getting faster and clearer with the Messages isn't actually going to matter, getting all the lighting requests actually right isn't going to matter, there's got to be something she could do that matters -
if we dig down deep enough, she asks between messages, are we outside the smoke, could we get a summons or teleport or Sending off then.
yes, Bastrade replies about a minute later. Callier burned all his spells digging into the bedrock and reached the boundary of the Dimension-Lock like effect he's sleeping, now, he'll try the Teleport in an hour and a half.
She's annoyed no one told her, even though she didn't, really, need to know.
They don't have an hour and a half, obviously. They've been pushed back to the innermost sanctum and the smoke's making it hard to breathe even in there. The fighters are going down and there's no spells left to get them back up. They're out of potions. They're out of scrolls. They have minutes, not hours.
She doesn't, actually, have any reason to think she can do it. But it's something that would matter, if it worked, and that's better than not trying anything that would matter even if it worked.
show me lesser planar binding, she whispers.
you think you can hang a fifth circle spell? He's too tired to sound incredulous, though it is very arrogant of her. She's twenty-six.
figure I'll die trying.
He doesn't have any illusion spells left, of course. He spits on his finger and traces the spell pattern in the smoky air. Her eyes are stinging. She tries to memorize it, tries to see it, the parts you can directly move and the parts that move quietly behind that.
She jumps into Callier's pit in the inner sanctum. The landing breaks her ankles, which really does not matter at all.
And she tries to hang her first fifth-circle spell.
It's not easy, but in a sense it feels like it should be harder. The air is more breathable down here, unless that's just her hallucinating from carbon dioxide poisoning. The spell slides around cooperatively like an old friend, like she was just hanging Detect Thoughts or something. She can hear her heart pounding and her skull throbbing to the beat, which is great because it helps her maintain her rhythm with the casting.
She draws out the binding circle on the ground.
And she tries to summon - well, actually, she kind of forgot the step where you specify what precisely you're trying to summon. Something that can cast Sending. Or Teleport. Or, frankly, something that can seal the pit above them so she can be overlooked by the demons when the innermost sanctum falls.