"he always causes discord" AT: "he is constantly looking for conflict and escalating it"
## Therefore ##
"For that reason"
## his disaster ##
That is the disaster that will happen to him, but also the disaster that he himself caused.
## overtake ##
That implies that the disaster is chasing him like a person or an animal, and that it will catch him soon. (See: [[rc://en/ta/man/translate/figs-personification]])
## in an instant, in a moment ##
Both mean the same thing, and one or both of them can be replaced by "suddenly" or "very quickly".