There is a total of 21 Riddles to solve in Suicide Squad: Kill The Justice League. All Collectibles are available for you to collect after you encounter The Riddler for the first time, as part of the main story mode.
There is between 1-3 Riddles per District. When you enter a District you will hear Enigma telling a Riddle and it will pop up at the top of the screen. To solve a Riddle, you need to find the specific item or area the Riddle describes. When you think you have found the area, hold “UP” on the D-Pad to scan the item. If you want to hear a Riddle again, open your map, hover over the specific District and press “L3” – this will cycle through the Riddles for the District.