Yongnuo YN568EX flashes, Yongnuo YN622N-TX flash commander and YN622N II triggers are a great combination if you are interested in off-camera lighting. Yongnuo YN568EX is the best Yongnuo flash for Nikon users, very similar to Nikon SB910 in terms of features and power output but much more affordable. YN622N II are the best radio triggers on the market. Pair them with YN622N-TX master unit and you have perfect kit for off-camera lighting.
Yongnuo YN622N-TX flash commander together with YN622N II transceivers allow you to trigger YN568EX flashes remotely. This master unit also gives you full remote control of YN568EX flashes. It is very convenient when flashes are mounted on light stands and you are using light modifiers. There is no need to go to the flash and change parameters, you can do everything remotely by adjusting them on YN622N-TX commander and these settings are immediately transmitted to flash units.
Yongnuo YN568EX flashes don't have built in wireless receiver so you need separate radio triggers to trigger them remotely. You need Yongnuo YN622N-TX commander mounted on camera and one YN622N receiver mounted on each YN568EX flash.