"....Hm."

Weiss isn't answering immediately. And this is going to be a big problem very soon. Weiss would pout and complain so much, if she didn't do anything.

Time to show off maybe?

Sinnah starts casting something she calls Bubble World. It'll take three rounds. 

(She also flies down and tags the civvie with her tail, granting them magical armor with one of the many enchanted silver-set diamonds nestled in it, and tries to extract them with the power of her flight.)

Enchanted armor and her assistance are enough to extricate the civilian with only a broken leg, though the shock is too much for them to do more than cling to her.

"Disintegrate." Part of the hamantula's chest is eaten away this time, turning to dust.

"Disintegrate." Another failure. 

Just as she's about to cast her fourth on the tentacle-entangled devil, the planar portal she's torn open starts to waver and destabilize. How will Sinnah's own spell interact with that? 

She's going to fly them clear of the tentacles and drop and/or forcefully un-cling them, not really paying attention to the fight and even less so to the unlucky civvie because she's still casting-

-This is a big one, the rhythm pounding like drumsticks on her skull as the energy wells up in sharp angles from her soul's reserve. Dozens of beats, all in very precise timing, helped along by the hand seals-

-And form. Bubble World.

Herself, the desperate Hellknight-hopeful, the devil, the portal, and the tentacles are all coming along into a grey shadow of a world, like it or not. Sound is muffled as if through thick cotton. The streets and buildings are flat grey stone. Any scent is gone, and the wind is different.

Anyone else within a 800 foot radius of Sinnah gets sudden magical knowledge of a magic spell separating the world in two, and a choice of whether to enter or stay out. Anyone walking into the shimmery grey border at the edge of the radius will get a similar choice.

And then she needs a few seconds to catch her metaphorical breath because Bubble World is awesome as all fuck, but it drowns out awareness and thought to complete.

This spell is, on a magical level, more like putting an enormous area-effect shield over a sphere of the Material, preventing things from interacting with each other, than something truly interplanar. Whatever the wavering portal does next will probably be the same as it was going to be... Hopefully bearable and kept separate from ordinary reality by the heavy weight of Abjuration poured into the Bubble World. Possibly to the Bubble World's detriment.

"What did you do?" The sorceress snaps, looking around. Her first impression is that they've been shunted to the Shadow Plane, but the knowledge imparted by the spell conflicts with that. She reflexively surrounds herself with a Wall of Force, then uses a Quickened Invisibility to conceal her exact position within the thirty-foot square perimeter of ten-foot high nigh-impenentrable walls while she surveys the situation.

In the meantime, the lightly injured hamantula hustles out from the tentacles and towards that perimeter to find and punish its summoner for this affront to its hellish dignity.

Behind it, the portal curls in on itself and collapses. Two more devils are shunted through, these ones towering pale insectile monstrosities armed with magical spears and wickedly sharp-tipped tails. In a silent telepathic exchange with the hamantula, the two gelugons learn of the circumstances of their arrival, and they silently lift off the ground in magical flight to pursue Sinnah.

Most other Korvosans within the 800' radius of the spell, upon receiving magical knowledge of a splitting of the Prime Material that they are invited to, politely and respectfully decline that invitation. (There are all sorts of stories about what the wizards of the Acadamae get up to in their rumored demiplanes, most of them unsavory.)

But not everyone is so wise. The Bubble World happens to be large enough to encompass a wizard-run restaurant, a Sable Company barracks, a pickpocket running from the merchant whose purse he just stole, several imps and house drakes, and indeed a small slice of the Acadamae. 

The population of this still stone version of Korvosa now numbers eighty-three.

"You invited collateral, you dumb fuck, no wonder they didn't want you."

And now she is pulling and casting one of her scrolls - of Adrenaline Surge - 

And reaching for one of the controls on her earrings, to pull it, activating the built in defensive spell, Aeroshell mk. XVII - a visible sphere of needle-like energies forms around her, even as she ascends.

The hamantula had recognized the spells the sorceress used, and in a bounding leap it catches the lip of the Wall of Force and vaults over. Now she is trapped in there with it, and it need only locate her.

The ice devils pursue Sinnah, diverging to approach from separate angles to reduce the risk of both being caught in the same spell. The spells she has cast are unfamiliar, so they each take a hand off their spears. As soon as they close to within sixty feet, they will unleash in synchrony two Cones of Cold at her, engulfing the space she occupies. Combined, this should be about as freezing as being engulfed in lava is hot. 

(In fairness to Jaeneska Hount, the sorceress, the Order of the Nail and other Hellknights generally are just as indifferent to collateral damage in pursuit of their aims. Their problem with her was her disrespect for the devils they emulate and seek to become.)