Stella was approaching faster than Twilight had anticipated. She'd grown into a rhythm, it was like she could predict where the walls would be and was acting ahead of coming across them, already prepared and knowing exactly what to do. Of course, that was impossible. The extent to which she seemed to be prepared for everything she met wasn't feasible, so it had to be something else. Yeah. Twilight realised it as she kept observing the other. It wasn't preparation for any particular obstacle, it was something else, something more general. Stella wasn't tackling her challenges individually. She had developed a single spell, one she permanently kept fed, that automatically worked to warp the space around her and let her through where she moved. She wasn't reacting to walls, she was expecting a wall and moving to slide around it at all times, regardless of the current situation. It was an extremely wasteful solution in terms of magical energy necessary, but if she could keep it up, and she clearly could, it also meant moving through the maze almost as quickly as if there had been no maze at all.
Twilight wondered if it was still worth it to keep delaying their by all means inevitable clash. Stella was tiring herself, sure, but she was tiring herself slower than Twilight. There was a limit to how much energy the latter could spend on keeping the former away before she needed the rest to actually face her, and with how taxing and fruitless the attempts at keeping Stella away were proving Twilight was starting to believe the moment of their direct confrontation would do best to come sooner than she'd thought.
So it would be then. She reached out to her pocket of reality one last time. Stella was still a small infinity and a while away from her, but the energy spent making sure she took her time to cross it wouldn't be worth losing given the fight that would come afterwards. Twilight's control permeated through the entirety of her stretched and twisted dimension, and she gave it all one single command, one single target. Collapse, and do so on Stella. She wasn't expecting it to defeat the alicorn, or even significantly hurt her, but it would still keep her occupied awhile.
The small universe the two ponies were in crumbled on itself in the equivalent of a sheet of paper getting crumpled before being thrown away, with a couple more dimensions and a lot more friction involved. Pieces of reality ground against each other with the sound of roaring black holes, heating up like stars and shooting off sparks and lightning. Like shards of glass falling down the entirety of everything around Stella converged in on her, like a cubist rendition of a violent carriage crash, and all the lengths and all the space and all the distance hammered itself towards her. The alicorn sensed it happening, through her magic more than anything, and quickly put up a shield.