Using CopyRegion on a large amount of terrain in a teamcreate place disconnects the user who excecuted the script. This prevents users in teamcreate from excecuting the function via command line, which is useful for things like exporting maps. In order to repro, generate a large amount of terrain in teamCreate and then run the following command:
local region = workspace.Terrain:CopyRegion(workspace.Terrain.MaxExtents) region.Parent = workspace
Pasting an already-created terrain region has the same crashing effect, and if a place contains the region, no user will be able to connect via teamcreate.
Was told to tag @Silent137