Space Agatha can jump to and re-emerge from beside an open stairwell, letting her escape a collapsing floor.
Akuma tells Carl that Agatha has a method that allows her to jump to the Waiting Room and reappear outside an open stairwell. It is why she slipped away before he could kill her, and why she will not likely be seen again on the ninth floor.
The trick effectively makes her immune to being cornered on a floor, and forces the hunt for her onto The Tenth Floor. Combined with Li Na's inability to locate those who are Marked for Death, it leaves the crawlers with no reliable way to find her at all.
Transit space Agatha exploits to escape floors before they close.