The goal is to get 15 kills using CZ75-Auto. CZ75 is just a regular auto pistol. It has good spread of fire, but very few rounds, so you need to make every bullet count. Below are three good locations that you can use to set up an ambush.
Going a bit further from the respawn, you can lean out from behind the wall to check whether any enemies are approaching. If they are, you can open fire right away or let your allies know and retreat to safety to prepare a response. Here you also can weaken the attack with grenades or other weapons - deal some damage to the enemies going up the stairs and it will be easier to get them later. Note that an enemy can also appear on the balcony on the right.
The picture above shows a corridor that's leading to the stairs, which can be used by the enemies to get to the building. There ends the playable area of the map. Looking behind the corner, you can see whether the enemies are planning to attack from that side. If they are, wait around the corner and open fire. Throwing a flashbang deeper into the corridor is also advisable - the enemies can be mowed down if you throw it well.
Right next to the respawn, there's a small cottage, and inside - an open hatch with a ladder. Using it, the enemies can infiltrate the building unnoticed and assault the bombsite. You should make it a habit to visit this place from time to time, especially since you've got a great vantage point here. Wait before the enemy shows their head to eliminate them quickly.
Remaining important information:
- The pistol used in this mission is the default gun. It has only 24 rounds/round - since the magazine can be emptied rather quickly, you need to make sure every shot is placed well.
- Try to aim for the head and upper portions of the enemies' body to deal the most damage and use the fewest rounds.
- Reloading the pistol takes a while, so you should always have a cover ready for that.
- Buy another gun for the money you get - it may come in handy at some point.
- You may try to weaken the enemies with another gun and only finish them with the pistol.
- If 5 enemies a wave is too much, you can kill one of them with a regular weapon and then pick up the remaining ones.
- Flashbangs are extremely useful in this mission, giving you more time to aim and shoot.
- When the enemies are storming the stairs to the corridor, throw in some flash grenades.
- If the enemies are storming through the sewage, you should wait near the open hatch and shoot as soon as you see enemy's head. Try not to lean over the hatch - the enemies will instantly open fire. Drop a flashbang first.