Gemini: Heroes Reborn

First of all, dozen means a group or set of twelve, so in order to unlock this trophy, you must kill at least 12 enemies via Deathtraps. Deathtraps in Gemini: Heroes Reborn are hazards. Hazards are hazardous objects that are highlighted with an icon that represents the danger type such as the following hazardous icon:
 

Hazardous objects can be used against your enemies to kill them in a variety of different ways. Hazardous objects will first start appearing in levels during Level 4: A Wrinkle and onward. To kill enemies, you must use your Telekinesis powers by holding to grab objects and then press to throw them into the hazardous object. Rinse and repeat this 12 more times throughout your playthrough until the trophy unlocks.

Additionally, there are a few more things that you must know. If you're killing enemies this way from the start of Level 4, then the earliest time the trophy can unlock is during Level 6: Going Down. If you still need the 12 kills, the best place is Level 15: Bonum Nox because the starting room is filled with hazardous objects and you're required to kill all the enemies in this area before moving on anyway. Last of all, you cannot farm this by killing yourself or by loading from the last checkpoint. Kills only carry over whenever you reached a new checkpoint.

Below is a list of all hazards

1. Giant Fans
2. Electrical circuits
3. Crush machines
4. Molten steel
5. Flame coming from pipes
6. Acid pools
7. Collapsing walkways