In the achievements list, one says complete 25 timed quests to win 25 crowns

[IomMeza]

Where are 25 timed quests? You can find the achievement called 'Timed Quest Master' in achievements list.

 

[DarkOmega]

Afte you complete a certain amount of regular quest you'll start receiving timed quest in your quest log, atleast that's how I think it works I already completed around 9 of them but they do take a while to start appearing.