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