This level will require you to clear out several casino rooms. They are going to be large and filled with a lot of objects. Thankfully, you shouldn't have any major problems winning these fights. You won't be saving any hostages here, so you don't have to worry about aiming precisely at your targets.
You start off in the same room (#1). I would recommend placing your team near the left door. Your men have to be ready for an assault. You could also tag two targets for them, however this won't be necessary. Head on to the right corridor (#2). You shouldn't have any problems finding it on your tactical map. Thankfully, you won't encounter any terrorists here.
Head on to the second door. I would recommend using a Snake came here. As you've probably noticed, some of the terrorists are standing on your left (#1). It would be wise to take them out in a first place. Proceed with the assault. If you're lucky, you should be able to take out most of the terrorists within 2-3 seconds (#2). Move back to your door, because more hostiles will arrive in this area very soon. You will have to use a cover if you want to neutralize them.
One of the terrorists should be hiding on your right (#1). Make sure that he's dead before you decide to move on any further. Sadly, it's not going to be that simple. You could use your scope or some of the carried grenades. Make sure that the rest of squad is providing you with a covering fire. After that, secure the left side of the room and take out the remaining bandits (#2).
You will have to start moving towards the middle part of this room. Thankfully, you will have a lot of objects that can be used for cover. Try killing enemy soldiers from a larger distance (#1). One of the terrorists should be hiding near the red car, however you will have an opportunity to surprise him (#2). Order your men to move forward, however don't send them to unchecked areas. Use your tactical map often, so you won't miss anyone along the way.
Once you've reached a corner, start heading towards a second large room. It's going to be located on your right. You will encounter a few additional soldiers near the entrance (#1). Once they're gone, order your teammates to hide behind walls (#2). As a result, they should be able to dispose of the remaining hostiles.
Keep heading towards your current destination. Make sure that you check your surroundings carefully, so you won't miss anything important. Some of the terrorists will be hiding behind slot machines (#1). Take them out from a larger distance. Order your men to stay here. Your teammates should start shooting at the remaining terrorists (#2). These hostiles are hiding behind the counter.
It would be wise to surprise these terrorists from the right flank. Activate your tactical map (#1), so you'll now exactly where to go. Start off by killing the terrorist that's standing closer to your position (#2). After that, head on to the right room and take care of his colleague. Once this is done, order your squad members to gather around your position.
Head on to the next door (#1). You shouldn't have any problems finding a correct path. There aren't any other corridors here. Additionally, you won't encounter any hostile units. You will come across a large elevator shaft (#2). Use the rope to slide down. Once you're there, wait for the rest of the squad to join you. Proceed to the next section.
Head on to a small tunnel. You will be getting closer to a much larger room. If you're lucky, you should be able to surprise some of the terrorists (#1). Once the first group has been eliminated, enter the room and hide behind a nearest cover. You will have to secure this entire area. After that, start moving towards the main vault (#2). The rest of the team should be following your lead.
Try entering a new room, however you will have to be very careful here. The first group of enemy soldiers will appear on your left (#1). This is going to be a difficult fight, mostly because you won't be able to use any covers right away. I would recommend choosing smaller containers for cover. You should be able to take out the remaining terrorists from here (#2). Don't forget about your teammates. They can provide a much needed help during these fights.
Make sure that this area has been properly secured (#1). You could check some of the nearby corridors, however this won't be necessary. Head on to the next large area of the map. You will come across a single terrorist along the way (#2). I would recommend aiming at his head, mostly because he won't pose as a serious threat. Turn on your nightvision goggles.
Once you've reached a small junction, turn left and open a door. You will come across a large staircase (#1). Use the stairs to get to the upper level of the complex. Doing this will allow you to surprise some of the terrorists. Keep moving towards your current destination. Head on to a large balcony. Make a few steps forward and start shooting at the visible enemy soldiers (#2). The terrorists are occupying the lower floor.
Order your men to hide behind some of the nearby pillars. It's very important that you do this quickly. A large group of enemy soldiers will arrive on the same level. They will appear on your left. Deal with this problem swiftly (#1). Once you've secured the entire area, start moving towards a glass room. It's a blue square on your tactical map (#2).
Enter this new room and head on to the left side of the screen. Order one of your teammates to hack into a security system of the casino (#1). Get ready, because your squad is going to be attacked by new terrorists very soon. You could try and take care of them from here (#2) or go back to one of the previously secured corridors. Thankfully, there are only a few terrorists for you to kill, so you shouldn't have any problems finishing this task.
Once you've dealt with these problems, exit the room and use the stairs (#1). The objective will be to reach the lower floor. Now you will have to go to a larger corridor that leads to the next section of the map (#2). Order your men to prepare for an assault (there's a door here). You, on the other hand, should proceed to the second door.
Step up closer to the door and use your camera. As you've probably noticed, two terrorists are standing here. Tag them, so your team won't have any problems finding them (#1). After that, proceed with the assault. I'd strongly recommend helping your team to solve this problem (#2). It would be best to kill the left terrorist. Thankfully, these guys won't even have a chance to respond to your attack.
Gather the rest of the squad around your position and head on to the next section of the map. You should be able to reach a new door very soon. Use your camera once again. There are two enemy soldiers here (#1). Tag them for your team. After that, order your men to begin the assault (#2). If you're lucky, you should be able to get rid of these terrorists without any major problems. Head on to a nearby staircase. This will allow you to end this level.