Despicable You Freeze Ray
During the very first section of Gears of War 4’s prologue, you’ll be taking on a mission in Aspho Fields. If you’re playing through the campaign on the Insane difficulty, then you’ll be able to get access to a pretty special gun. Once you’ve ran through some blast doors, you’ll see a garage door slowly closing. Make it inside here and look for the weapon called Despicable You.
Equip this and you’ll now be able to freeze your enemies. Shoot them once with any other weapon to see them explode in a bloody mess. Delightful!