Showdown
/ˈʃəʊdaʊn/
Definition 1 of 3
Pro Tip 1/3Final Conflict
Refers to the last event that decides the outcome of an ongoing struggle or competition. 
After months of debate, the committee is ready for a showdown.
Pro Tip 2/3High Stakes
Used when the outcome is very important to those involved. 
The championship's showdown will be the game of their lives.
Pro Tip 3/3Anticipation and Tension
Often implies a buildup of anticipation or tension leading to the event. 
The heated campaign ended with an electoral showdown.