First referenced:
The Desolate Guardians (Part 3)
Other references:
'I think I may have somehow missed the end of the world... (Part 3)'
Described as a jagged, glowing purple rift in space and time, the Purple Slice appears to cause people observing it to go temporarily insane, and attempt to claw their own eyes out or cause other forms of self harm. The prescribed method for dealing with purple slice is to tie yourself up sufficiently well to prevent self harm, but loosely enough to escape subsequently to avoid other dangers.
Heath communicated these instructions to survivors, who accidentally misinterpreted them as tying the rift up. This proved to be futile as expansion of the rift promptly tore through the rope and continued to expand.