Two allies or two clan-mates can launch a Joint Attack (JA), both they can join to the attack troops from any number of their domains.
When launching an attack you can invite to join all your clan-mates or all your allies but only 1 player will be actually able to join the attack.
Outer Domain will NOT become visible for invitees just for being invited.
There is a separate interface for sharing information on Outer Domains – the "Domain Report" button in a Domain’s menu. If you want to report a domain to several players - list their nicknames separated by space or comma.

How Joint Attack is sent:
You and your ally (or clan-mate) should decide who will be the mission initiator. Usually it is decided according to the distance between attackers’ cities and target. Mission with the longest distance (and so – time) should be launched first, so that ally (or clan-mate) was in time for joining. If distances are equal, any can be an initiator and launch an attack on the slow speed and ally (or clan-mate) will join on faster speed.

а) Mission initiator should open the "Attack" window (a window of launching attack), choose troops, mission type and mission speed there.
Then it is needed to choose "Invite" and then – "allies" (or "clan-mates").

b) After that, ally (or clan-mate) should also open the "Attack" window and choose "Join" and then – initiator’s name in the list. If there are several missions in the list, the earliest launched mission will be shown above and the latest launched – below.

Missions from other your domains can be joined in the same way.

All participating in Joint Attack troops’ arrival will happen at the same time. Whereas return of each mission will happen at different time depending on missions’ speed and distance from target.

How to join to your own troops:
You can take your own troops from other domains in a Joint Attack.
In order to do this you should:
a) launch first mission in a usual way, b) when launching second squad’s mission set "Join" and choose "Your own Nickname" in the appropriate boxes.

Up to 3 players (together with owner of a domain) can participate in joint defence of the domain. In order to send assistance allies or clan-mates should click (on the Kingdom Map) the domain where assistance is needed and choose the "Assistance" button in the domain’s menu.
Troops from any amount of domains of one player can be sent for assistance in such way.
Each mission will arrive at its own scheduled time according to distance between the home and destination domains.
Staying Time can be specified for each squad.

Attack possibility is checked, according to the Ranks Rule, separately for initiator and for those who join, so when planning an attack choose allies of the appropriate ranks.

Resources Share:
Resources and the Black Gems are shared by half. If someone of the players doesn’t have enough Carriers to carry his half off, they will burn down.
If there are, for example, 5 Black Gems, then initiator will receive 3 of them and the one who joined – the rest 2.

Mission Withdrawal:
There’s a rule: if joint mission initiator withdraws ALL his squads from the mission, then all joint squads will be withdrawn too. However, if at least one initiator’s squad is in mission – the mission continues.

Elf launched mission and Knight joined it.
Elf withdrew his mission – Knight’s mission is automatically withdrawn and turns back.

Elf launched mission and Knight joined it.
Elf joined one more squad to the mission.
Elf withdrew his first joined squad – the mission continues as there is one more Elf’s squad in the mission.

A player launched a mission from his distant city and joined the mission from his near city.
Attack from the distant city was withdrawn – attack from the near city continues.