Zenith – /ˈzēnəTH/ – noun – 

  1. the highest point reached by a celestial or other object
  2. the point in the sky or celestial sphere directly above an observer
  3. the time at which something is most powerful or successful.

Note: Also a time frequently used in anime or fantasy for some dark creature to be summoned to our realm only for the main character to slay them instantly in a display super cool abilities.