Gadwall Trophy in The Psychoduck

Story related. Cannot be missed.

Level 7 will take place at night with lanterns being placed in some of the grey blocks you will come across, while level 8 takes place during the day once again. Both levels use the same principles found in level 6, so be sure to make use of the grey blocks and hide from the guards when possible to prevent yourself from being caught by them or the heron as you approach the latter.

You will unlock this trophy once you complete the eighth level for the first time.