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