Attack-synchronisation is used to coordinate both attack and support movements originating from several castles. The arrival of an existing troop movement serves as a basis for further attacks, so that all attacks arrive at the exact same second. It is however only possible to slow down troop movements, therefore you can only select units which are able to reach the destination on time.
Starting the Synchronisation
The button for synchronisation is shown in the transit column of the active castle under the following conditions. If the castle is close enough to the target, so that all its units can get there in the remaining time, then the button is shown without any restrictions. If the castle is close enough to the target, so that fast units can get there on time, but slower ones can’t, then the button is shown, but the troop selection phase will be restricted. Should the castle be too far away from the target, the button will not be shown and no attack-synchronisation is possible.
The attack-synchronisation is made in the following screen. The time arrival of the existing troop movement is shown beneath the target. Now you can choose the troops you want to send. If this is for an attack, you may choose to select silver. If the unit is not able to reach the preexisting troop movement, then it will be faded out and you can not synchronise your attack with it. It is possible to see under the transport time, how long the delay is with which the selected troops arrive to their destination.
Starting the Attack-synchronisation
A new transit of the corresponding type is created once the button for the attack-synchronisation is pressed. Its time of arrival equals that of the previous selected transit.
U.S. Patent Publ. No. US 2014/0229893 A1