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