終わる => to finish; to end N4
[後「あと」]で => After V1, V2 N5
Time
[終「お」]わる => To finish A; A ends N4
Secondary Verb
〜がさいご(が最後) => if you do... negative result N1
Decisive (resolute decision)
たが[最後「さいご」] => Once A occurs, B happens N1
Information, Report