So I came back at the website and found out that the Trivia Challenge is not just a mere event but it's a permanent feature.
Daily Quiz System
Here's some additional info:
-> Players level 10 and above can actively participate in this.
-> No time limit in answering the questions.
-> Questions change every time.
-> Once you get to the Elsword Logo on the board, answer the questions correctly, you'll automatically get these prizes:
--> 7th block 高級魔法石 (Ruby)
--> 14th block Full HP & MP Potion
--> 21th block "+5 Upgrade Scroll"
-> After the end of the month, the system will reward you with a prize depending on what block you've arrived at. Prizes range from: " Unknown Elstones" , "Full HP & MP Potion" , "+7 Upgrade Scroll"
-> Also, at the first day of the month, you'll automatically be returned at the start of the board .