As she approaches, it swings wrecking balls at her, but she's fast enough to dodge.  When she wounds it, it screams, a horrible sound like a metal girder tearing, and begins to claw at her with enormous backhoe-legs.

She dodges what she can, parries what she can't, and tries to cut off a few legs at the joint for good measure. 

She takes out a couple before a backhoe with a shovel-claw as big as her entire body scoops her up and flings her across the sphere.

It shudders, then begins tearing open the tower its standing on, folding up its spines and burrowing downward.

She slows herself down midair, bounces back over, and pursues.

By the time she gets back over, the tunnel the witch carved is seething with familiars.  As soon as they see her they start swarming toward her on all fours.

Swing through those, manifest a sword to skewer that conveniently clustered group, toss that one away from her with ribbons when it nearly gets behind her - 

She has the feeling that Kaylee will catch up before she makes it through this.

And, indeed:

'Lianne, I found the witch, it's on the inside of a big globe, coming up out of the floor - where are you?'

'Trying to follow it, I don't know how quickly I can get through these familiars - be careful, it's pretty difficult to take on at range.'

'I'll see what I can do.'

She leaps and rockets through the air toward the witch, conjuring up arrays of knives in midair and sending them spinning through the air toward it.  As she gets closer, she conjures a pair of Bowie knives, but before she can close the gap it swats her aside with one of its legs, then heaves and twists its entire body to send three enormous wrecking balls in her direction.  She only just manages to scramble to her feet and jump backward out of the way.

She goes in for another approach, this time from above: she leaps into the air and springboards off of nothing in midair, shooting down toward it at an angle that she hopes won't let it send another wrecking ball toward her.  Instead, it scoops up a bundle of familiars and hurls them at her; she stabs one in midair, springboards off another, and flings knives toward it and the remaining two as she shoots away.

She lands some distance clear of the witch, and grimaces.

She spots a flash of gold rocketing across the chamber toward the witch.

"Lianne?" she calls out, in ordinary speech.

But no, it isn't Lianne - the color scheme's the same, but the new girl came from the wrong direction, and Lianne isn't that fast...

Whoever it is has a long, slender sword in each hand, and manages to slash apart three or four more flung familiars in midair before she lands on the witch.

"Who the hell's Lianne?" she calls back.  "Listen, I don't care if this is your territory - " she stabs another familiar and leaves the sword embedded " - I've spent months tracking this thing down, it's mine, get your own."

"I'm not - we can work together, can we work together?"

"You any good at range?  Keep these crawly fuckers off me!"

"Got it!"

She is pretty good at range, in fact, and she's been practicing taking shots from midair; she manages to jump and hover and prevent any spare familiars from getting close to the mysterious new girl.

'Lianne, somebody new showed up, she's taking care of the witch and I'm keeping familiars off her but I don't know if she can finish it on her own or not, how are you doing?'

'Just - about - there!' And she slices through the last familiar, then darts for Kaylee and the witch, clearing her grief seed as she goes.

When she gets into the sphere, she takes a moment to orient herself, then leaps for the witch, sword at the ready.

A few more familiars head toward her but Kaylee manages to head them off from afar, and she lands successfully on the witch.

"You must be Lianne," new girl deadpans.  (Up close, it becomes clear that she's a few years older than either of them.  Also, her weapons aren't exactly swords - they're sword-like, but the handles are just about as long as the blades.)  "Your friend's got us covered pretty well.  Let's take this thing down."  She nods to the middle of the giant cluster of cranes and starts climbing downwards.

"Let's."

Lianne follows, occasionally sticking a sword in a joint, at the ready in case the witch retaliates.

It does: once again it starts clawing at the interlopers with enormous mechanical claws.  The new girl is fast and nimble enough to dodge out of the way as she climbs down.

Lianne isn't always, but her swords are sturdy and she swings hard, and now she's on the look out for the trick from earlier.

Soon they're near enough to the center or the witch for New Girl to start doing her level best to turn its insides into a gold sword-staff pincushion.

She can be joined by Lianne's giant swords, as many as she can economically summon, applied as strategically as she knows how - mostly fouling up joints and in anything delicate-looking. She grabs existing swords and yanks them out before throwing them elsewhere on occasion.

Stab!  Stab!  Stab stab stab!

The witch's screams get progressively more pained and ear-rending, until eventually - 

"Shit, get clear - "

 - the witch's body starts collapsing around them.

Screw economy, she's cutting her way clear, summoning swords left and right to prop up an exit.

New Girl doesn't bother trying to cut anything out of the way, just springs and leaps and dodges through the air as fast as she can.

They escape just as the witch collapses into a pile of rubble.