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