To unlock the Klassic trophy in Mortal Kombat 11, you will need to complete a Novice, Warrior of Klassic tower for the first time. There is a second trophy for completing the above towers 10 times with different characters, that you can combine this trophy with:
The easiest way to do this is to allow the AI to fight for you.
From the Main Menu > Konquer > Klassic Towers > Novice
Select a character of your choosing with
and press
to turn on the AI fighter. You will only need to press
between each fight to continue. After the 5th opponent is defeated, you will unlock the ending for your chosen fighter and unlock the Klassic Tower trophy.