Clash-of-clans – What does the Black shield icon mean for clan war availability

This symbol means that those player can participate in clan's war, The other players who don't have it are spectators and they can't participate in war.

The logic behind that is like this :

• If a player join your clan after you started the war they will become a spectator and will not be able to actively participate in the clan war.
• If your clan members are more than enemy's clan, The players who have lowest trophies will become spectator so both clans have the same number of members ( e.g 30 vs 30 or 45 vs 45)

The only requirement is that a clan must have at least 5 members eligible for war. (This used to be 10, but 5 vs 5 war size is also available now.)

Members who are new to your clan will be ineligible for war if they left their previous clan while a war was in progress. They will become eligible for war again when the previous war is completed. You can check your clan member list to see if any members are ineligible for war, and see when they will be eligible again. If you start the clan war while members are still ineligible, those members will not be able to participate.

You can see when players will be eligible in their profile through clan's chat room.