In the rich text editor:
@KingOfChaos
In a comment:
[KingOfChaos](https://chowlings.com/user/KingOfChaos)
For Names and Avatars:
In the rich text editor:
%KingOfChaos
In a comment:
[](https://chowlings.com/user/KingOfChaos) [KingOfChaos](https://chowlings.com/user/KingOfChaos)