After defeating the Tentacle, and gaining access to Area 2, you will find the schematic for
Hypno Trap at the top of the stairs leading into the area. You'll need to pick this up in order to get this achievement. Next, you will want to use the drill to open the available doors in the area before drilling any hives. Inside these areas, you will find red toolboxes that are full of the parts required in order to complete your schematic. Find 3 red toolboxes in order to complete the schematic. Now your Hypno Trap is ready to be used, by pressing the
Back button to bring up your loadout menu, and then pressing X to select the Hypno Trap. The Hypno Trap can then be placed on the ground by using the trigger.
You'll want to wait until a Rhino appears in order to get the achievement. Also, having a flare ready makes this trophy even easier. Once a Rhino appears, use a flare to gather small enemies in one area if available, and then get the attention of the Rhino. You'll want to place the trap directly UNDER the Rhino if possible, or extremely close to its path. The trap will ONLY convert the first two enemies that touch it, so make sure that other smaller enemies don't accidentally step on it before the Rhino. You can shoot the Rhino in order to get its attention and make it run towards you and the trap. Once it touches the trap, it will become friendly, and the trophy will unlock.