To create a war alliance, you need to reach 500,000 gold coins and level 50 or above. After completing the main mission, open the war alliance at the War Alliance Messenger in Icewind Valley. You can create it. Click on Alliance.
Here you can see the conditions for creating a war alliance and choose to enter a name.
Then click Create.
After the creation is completed, you can click to view the rankings of some other people's alliances and your own alliances.
Click Alliance Construction to build your own alliance. After creating it, remember to invite others to join.
