cru·ci·ble
 /ˈkruːsəbəl/  noun  ,  pl   -ci·bles [  count  ]
  1 : a pot in which metals or other substances are heated to a very high temperature or melted
  2 formal + literary : a difficult test or challenge
   He's ready to face the crucible of the Olympics.
  3 formal + literary : a place or situation that forces people to change or make difficult decisions
   His character was formed in the crucible of war.