I would say you should first complete the tower in front of you, where you have to climb up the platforms and grab the light prism sitting on the top. You don't have to face any enemies or solve a complicated puzzle. Though it may seem easy, it's impressive if you can complete it in one go. After that, you should focus on the tower to your left, where you have to fight the waves of enemies and defeat them to obtain chests. You've been fighting enemies throughout the game and will continue to do so. Fighting them in a challenge won't be any different. The difference being the enemies here may pose a difficulty if your characters aren't adequately invested in artifacts, weapons, and levels. Lastly, you should focus on the fire puzzle tower in the end as it may require you to figure out their patterns and a bunch of tries to solve them. Feel free to go through their solutions on Youtube because it may happen that referring to multiple sources makes things clear in your head. I highly recommend you to pay attention to minor details when completing puzzles and try them on your own first.