Just Cause 3

There are only 2 Challenges in the new DLC and both of them are not to hard.

One can be found in the Weapon Shipment Yard - Nebio Sud after liberating

The other is found in the Weapons Warehouse - Nebio Nord after liberating

Speed is the key to these challenges. If you are not constantly moving towards the next target then you will be wasting time. The quicker you do each round the more bonus you get. Don't wait for them to come to you as some enemies just drive around in a loop.

Using you main weapon (RT) seems like the natural thing to do but it is actually a hindrance as it takes to long to kill the enemies causing you to waste time and you don't get any bonuses for using it.

Only use the (RT) on the paratrooper plane. The Paratroopers only appear on the Weapon Shipment Yard Challenge. With these look towards the sea as soon as the round starts and unload into the plane with (RT). Do this quickly and you will kill them all before they jump out. Saving a lot of time because if they get out its a pain to shoot them down.

Using the notifications at the top of the screen to help give you a heads up in what enemies are coming next.

Use (LB) on these enemies to potentially get a Strike Bonus:
Soilders
Armoured Vehicules
Mechs

Use (LT) on these enemies to potentially get a Thrown Bonus:
Helicopters
Tanks
Drones

Hope this helps someone