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