In the rich text editor:
@Corias
In a comment:
[Corias](https://chowlings.com/user/Corias)
For Names and Avatars:
In the rich text editor:
%Corias
In a comment:
[![Corias's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/Corias) [Corias](https://chowlings.com/user/Corias)