In the rich text editor:
@t0xicgrave
In a comment:
[t0xicgrave](https://chowlings.com/user/t0xicgrave)
For Names and Avatars:
In the rich text editor:
%t0xicgrave
In a comment:
[![t0xicgrave's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/t0xicgrave) [t0xicgrave](https://chowlings.com/user/t0xicgrave)