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